A wet riser is a vertical fire main of at least 100 mm, kept permanently full of water under pressure by the building's fire pumps, with a landing valve on every floor. Firefighters connect their hoses to it instead of laying hose up the stairs. NBCS 2026 Part F defines it in clause 2.70.

What is the difference between a wet riser and a dry riser?

A wet riser is always full of water under pressure from the building's pumps. A dry riser stays empty until a fire engine pumps water in through an inlet at ground level, so water reaches the floors later. NBCS 2026 allows a dry riser instead only up to 24 m with a reliable public hydrant main, or in very cold places.

What is a downcomer in fire fighting?

A down-comer is a fire main of at least 100 mm fed from the terrace tank by a terrace pump, with a landing valve on each floor, a ground-level inlet for fire engines and an air release valve at the roof. NBC 2016 uses it in flats of 15 m to 35 m.

What size is a wet riser pipe?

At least 100 mm. Table 8 of NBCS 2026 Part F sets 100 mm with a 63 mm landing valve for most buildings up to 15 m, and 150 mm for hotels, institutional and business buildings above 15 m and for industrial, storage and hazardous buildings up to 15 m.

What pressure should a wet riser give?

At least 3.5 bar at the highest and the hydraulically remotest hydrant, and no more than 7 bar at any hydrant, so the hose stays safe to hold. Lower floors use orifice plates or pressure-controlled valves to stay under the limit.

Which IS code covers wet risers?

IS 3844:1989, the code of practice for internal fire hydrants and hose reels, which is still the current edition on the BIS database. Water supplies follow IS 9668:1990, fire pumps IS 15301:2003 and landing valves IS 5290:2025.

From what height is a wet riser compulsory?

It depends on your state's rules. Under NBC 2016 Table 7, flats and hostels need a down-comer from 15 m and a wet riser above 35 m. Under NBCS 2026 the trigger is floor area as well as height: apartments of 1,001 m² and above get a wet riser.

How big should the fire tank be for a wet riser?

NBC 2016 sets 75,000 litres underground for flats above 35 m, 1,50,000 above 45 m and 2,00,000 above 60 m, plus a terrace tank. NBCS 2026 works it out from flow and a duration of 30 to 120 minutes instead of printing litres.

Fire safety glossary 21 min read

Wet riser: what it is, how it differs from a dry riser and a down-comer, and when India's codes require one

Updated October 2026By Flamekite Editorial DeskFacts checked against official sources on 24 October 2026

Quick answer

A wet riser is a fire main of at least 100 mm, kept full of water under pressure, with a landing valve on every floor and 3.5 to 7 bar at the hydrants. That is the definition in NBCS 2026 Part F, clause 2.70, and the pressure rule in clause 5.1.1(f).

A dry riser stays empty until the fire service pumps water into it. A down-comer is fed from the terrace tank by a terrace pump. Under NBC 2016 Table 7, which many state rules still follow, flats and hostels of 15 m to 35 m need a down-comer, and those above 35 m a wet riser with a 75,000 to 2,00,000 litre underground tank.

Minimum riser main: 100 mm; 150 mm for some uses above 15 m; At a glance
Pressure at the hydrants: 3.5 to 7 bar; Lowest at the top, highest at the bottom; The numbers
Flats need a wet riser above: 35 m; NBC 2016 Table 7; a down-comer from 15 m; Height table
Installation code: IS 3844:1989; Still current at BIS; Standards

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Wet riser at a glance

What the national standard and the BIS database say about a wet riser, with the source of each line.
What	The rule	Source
What it is	A vertical fire main of at least 100 mm nominal diameter, permanently full of water from a pressurised supply, with a landing valve on each floor or landing (NBCS 2026 Part F, clause 2.70)	BIS, SP 7:2026
Also written into state law	Tripura's Fire Safety Rules, 2026 repeat the same definition word for word in their definitions list, item (76)	Directorate of Fire and Emergency Services, Tripura
Size of the main	100 mm with a single 63 mm landing valve for most buildings up to 15 m; 150 mm for hotels, institutional and business buildings above 15 m (Table 8)	BIS, SP 7:2026
Pressure	At least 3.5 bar at the highest and the hydraulically remotest hydrant, and no more than 7.0 bar anywhere (clause 5.1.1(f))	BIS, SP 7:2026
Hose reels	On every floor where the occupancy table asks for them, connected straight to the riser, with hose of at least 19 mm (clause 5.1.1(d))	BIS, SP 7:2026
At the terrace	Wet risers are joined in a ring, with a cut-off valve on each connection so one riser can be repaired while the rest stay live (clause 5.1.1(e))	BIS, SP 7:2026
Pumps	An electric pump with a standby of equal capacity, plus a jockey pump to make up pressure losses (Table 7M, note 1)	BIS, SP 7:2026
Water storage	Two or more interconnected compartments of equal size, so one can be cleaned while the other stays full (clause 5.1.2.1)	BIS, SP 7:2026
When flats need one (NBC 2016)	Above 35 m in height; from 15 m to 35 m a down-comer is enough (Part 4, Table 7)	NBC 2016, Part 4
Installation code	IS 3844:1989, internal fire hydrants and hose reels, current on the BIS database and valid to 20 June 2030	BIS standards database

Wet riser vs dry riser vs down-comer

The three ways a building carries water up to its floors, as NBCS 2026 Part F defines them, with where each code uses them.
Option	Wet riser	Dry riser	Down-comer	Source
Water in the pipe before a fire	Always full, under pressure	None: the pipe stands empty	Full, from the terrace tank	BIS, SP 7:2026
What feeds it	The building's own fire pumps	Fire service pumps, through an inlet at ground level	The terrace tank, through a terrace pump, gate valve and non-return valve	BIS, SP 7:2026
Minimum main	100 mm nominal diameter	100 mm internal diameter	100 mm internal diameter	BIS, SP 7:2026
Fittings named in the definition	A landing valve on each floor	A landing valve on each floor	A landing valve on each floor, a ground-level inlet for fire service pumps and an air release valve at the roof	BIS, SP 7:2026
Flats and hostels under NBC 2016 Table 7	Above 35 m	Note 24: in hilly or industrial areas, or as the local authority requires	15 m to 35 m	NBC 2016, Part 4
Apartments under NBCS 2026 Table 7A	1,001 m² and above (level HL-3) and every tower above 60 m	In place of a wet riser up to 24 m, where a public hydrant main gives the flow and pressure 24 hours a day, or where it gets colder than 4 °C	501 m² to 1,000 m² (level HL-2); above 60 m, as a gravity back-up to multi-level pumping	BIS, SP 7:2026

How a wet riser is sized and approved, step by step

Fix the occupancy and the height
Find the building's group (A to K in NBCS 2026, A to J in NBC 2016) and its height measured from where the fire engine stands. Those two facts pick the row in the installation table.
Read which riser the row asks for
In NBC 2016 Table 7 the row says wet riser, down-comer or neither. In NBCS 2026 Tables 7A to 7J it gives the same answer plus a protection level, HL-1 to HL-6 for hose only or CL-1 to CL-8 with sprinklers.
Size the flow and the pumps
NBC 2016 names pump sets in its notes, such as 2,280 litres a minute with a 180 litre jockey. NBCS 2026 Table 7M works from hose streams: level HL-3 is 4 streams of 270 litres a minute and a 1,514 lpm pump with an equal standby.
Size the mains and zone the riser
Use 100 mm or 150 mm mains from Table 8, and split tall risers into zones or fit orifice plates so every hydrant sits between 3.5 and 7 bar.
Size the tank
Store the water in two equal, interconnected compartments. Use the litres your state's table names; where it follows NBCS 2026, the reserve is flow multiplied by a duration of 30 to 120 minutes.
Show it on the fire NOC drawings
Mark the risers, landing valves, hose reels, pump room, tanks and the fire brigade inlets on the plans the fire service approves, then build to them.
Keep it certified
Test it and file what your state asks for. In Maharashtra that is Form B from a licensed agency every January and July.

Wet riser by height in NBC 2016 Table 7: flats and hostels

NBC 2016 Part 4 Table 7 sets the riser, the tanks and the pumps by height for dormitories (A-3) and apartments (A-4). Many state rules still point to it, even though BIS withdrew it on 30 April 2026.

	Riser	Underground tank (litres)	Terrace tank (litres)	Pumps
Under 15 m NBC 2016, Part 4	None: extinguishers and a hose reel	Not required	5,000, plus 5,000 with a basement over 200 m²	450 litres a minute at the terrace, plus 450 with such a basement
15 m to 35 m NBC 2016, Part 4	Down-comer	Not required	25,000	900 litres a minute at the terrace
Above 35 m to 45 m NBC 2016, Part 4	Wet riser	75,000	5,000	One electric and one diesel standby of 2,280 litres a minute, and a 180 jockey (note 10)
Above 45 m to 60 m NBC 2016, Part 4	Wet riser and yard hydrant	1,50,000	10,000	Two electric and one diesel of 2,280, and two 180 jockeys (note 11)
Above 60 m NBC 2016, Part 4	Wet riser and yard hydrant	2,00,000	10,000	Two electric and one diesel of 2,850, and two 180 jockeys; multi-stage or VFD pumps for the lower floors (notes 12, 13)

Read from the page images of the NBC 2016 copy the Puducherry Fire Service hosts. Note 22: one set of pumps for every 100 hydrants, at most two sets, joined at their delivery headers. Note 23: instead of a second set, an extra diesel pump of the same capacity and double the tank. Hotels under 15 m with 300 m² to 1,000 m² on a floor need a wet riser above ground plus one, with 10,000 litres underground for every 500 m², at least 50,000.

Wet riser or down-comer under NBCS 2026 Tables 7A to 7E

NBCS 2026 replaced the single height table with one table per occupancy and a protection level per row. Find the line that matches your building.

If Flats, hostels, hotels or a school of up to 500 m² and up to 24 m (both)
Self-certification by a certified, state-approved building professional is acceptable. For offices the same line is 500 m² and 15 m. BIS, SP 7:2026
If Apartments of 501 m² to 1,000 m², up to 60 m (level HL-2)
A down-comer, extinguishers and hose reels. No wet riser, no yard hydrant. BIS, SP 7:2026
If Apartments of 1,001 m² and above, up to 60 m (level HL-3)
A wet riser and a yard hydrant, with detection and a public address system. No down-comer and no sprinklers. BIS, SP 7:2026
If Apartments above 60 m (level CL-4)
Wet riser, yard hydrant and sprinklers, with multi-level pumping and storage; pumps no higher than 12 bar shut-off. BIS, SP 7:2026
If Hotels up to 24 m: 501 m² to 1,000 m² (HL-3), or 1,001 m² and above (CL-3)
The smaller hotel gets a down-comer; the larger one a wet riser and sprinklers, without a yard hydrant. BIS, SP 7:2026
If Offices under 15 m: 500 m² to 1,000 m² (CL-2), or 1,001 m² and above (CL-3 or CL-4)
The smaller office gets a down-comer with sprinklers; the larger one a wet riser, yard hydrant and sprinklers. BIS, SP 7:2026
If Up to 24 m on hose-only (HL) protection, where a public hydrant main gives full flow and pressure 24 hours a day
A dry riser may replace the wet riser, its pumps and its storage, checked every quarter (Remark 1 under each table). BIS, SP 7:2026

Wet riser numbers from NBCS 2026 Part F

The figures a designer and an inspecting officer check first.

100 mm
Smallest wet riser, dry riser or down-comer main (clauses 2.10, 2.11, 2.70) BIS, SP 7:2026
63 mm
Landing valve outlet on each floor (Table 8) BIS, SP 7:2026
3.5 bar
Least pressure at the highest and remotest hydrant; the pressure range is 3.5 to 7 bar (clause 5.1.1(f)) BIS, SP 7:2026
7 bar
Most pressure at any hydrant, for the firefighters' safety (clause 5.1.1(f)) BIS, SP 7:2026
19 mm
Smallest first-aid hose reel, fed straight from the riser (clause 5.1.1(d)) BIS, SP 7:2026
5 m
Furthest a stair-side hydrant may be from the fire exit door (clause 5.1.1(g)) BIS, SP 7:2026
7 m
Deepest an underground fire tank may be below the fire brigade draw-out level (clause 5.1.2.1) BIS, SP 7:2026
12 bar
Highest pump shut-off pressure for towers above 60 m (Table 7A, note 5) BIS, SP 7:2026

How water travels through a wet riser system

From the tank to the nozzle, each stage has its own clause in NBCS 2026 Part F.

The fire tank
Two or more equal, interconnected compartments. Domestic pumps may draw only the overflow, so the fire reserve never drops; an underground tank is no deeper than 7 m (clause 5.1.2.1). BIS, SP 7:2026
The fire brigade connections
A collecting head with four 63 mm inlets on a 150 mm pipe lets fire engines fill the tank, at 2,250 litres a minute where it is in a basement or out of their reach; a 63 mm draw-out on a 100 mm pipe lets them pump from it (clause 5.1.2.1). BIS, SP 7:2026
The pump room
The main electric pump, an equal standby and a jockey pump, reached from ground level, no lower than the second basement, behind 120 minute walls and doors, with no submersible or negative-suction pumps (clause 5.1.2.2). BIS, SP 7:2026
The riser main
100 mm or 150 mm by Table 8, zoned so pressures stay between 3.5 and 7 bar, with orifice plates or pressure-controlled valves on the lower floors (clause 5.1.1(a), (f)). BIS, SP 7:2026
The landing valve and hose reel
In the firefighting shaft lobby, or within 5 m of the fire exit door, in a cabinet marked FIRE HOSE CABINET in 75 mm letters (clause 5.1.1(g)). BIS, SP 7:2026
The terrace ring
All wet risers joined at the terrace with a cut-off on each, so water can reach a floor from more than one riser (clause 5.1.1(e)). BIS, SP 7:2026

Wet riser parts named on a fire drawing

Ten words you will meet on a riser schematic or a fire NOC drawing, and the standard or clause behind each.

Landing valve: The outlet valve on each floor where firefighters connect their hose: 63 mm on a 100 mm or 150 mm main. Its current product standard is IS 5290:2025. BIS standards database
First-aid hose reel: A reel of hose of at least 19 mm, connected directly to the riser, for occupants to use first. Product standard IS 884:2025. BIS standards database
Jockey pump: A small pump that tops up pressure lost to small leaks, so the main pump does not start for nothing. NBC 2016 sized it at 180 litres a minute. NBC 2016, Part 4
Standby pump: A second main pump of equal capacity, a diesel pump in the typical NBCS layout, which runs when the electric pump or power fails. BIS, SP 7:2026
Fire brigade collecting head: A valve box at street level with four 63 mm inlets, two for a 1,400 litre a minute pump, through which fire engines fill the tank. BIS, SP 7:2026
Air release valve: Fitted at the roof on a down-comer so trapped air can escape when the pipe is charged. BIS, SP 7:2026
Orifice plate: A plate in a landing valve that cuts pressure on the lower floors to stay under 7 bar; a pressure-controlled hydrant valve does the same job. BIS, SP 7:2026
Installation control valve (ICV): The main control valve of a tower's system; it may sit in the first basement inside a room of 120 minute fire resistance. BIS, SP 7:2026
Yard hydrant: An external hydrant around the building, fed from the same pumps. External hydrant systems follow IS 13039:2014. BIS standards database
Firefighting shaft: The protected stair, lift and lobby that firefighters use; its lobby holds the wet riser, landing valve and talk-back (clause 2.24, Fig. 4). BIS, SP 7:2026

Mizoram's 30 m hose-reach rule for wet riser outlets

Mizoram's 2026 amendment says how far apart the outlets may be, a distance Flamekite did not find in clause 5.1.1 of NBCS 2026 Part F.

Word for word

Internal hydrants or landing valves shall be so arranged that every part of the floor area is within thirty metres hose reach from a hydrant point.

Mizoram Fire and Emergency Services (Superintendence and Control of the Fire Force and Fire Safety and Prevention) (Amendment) Rules, 2026, rule 57(B)(1)(a), Notification No. B-20011/2/2026-HM(F&ES), 20 August 2026 Mizoram Home Dept

The next sub-rule spaces external hydrants about 45 m apart around buildings and along fire access roads. A designer in Mizoram counts landing valves from these distances; elsewhere the count comes from the occupancy table and the fire service's review.

Wet riser rules in 6 states: worked buildings

The same riser question gets different answers state by state, because each state writes its own schedule.

Case 1
A 16 m, ground plus 4 apartment block in Imphal
Manipur, residential, between 15 m and 35 m.
What applies Schedule I of Act 9 of 2026 asks for a down-comer, a 25,000 litre terrace tank and a 900 litre a minute terrace pump, the same as NBC 2016. Government of Manipur
Case 2
A 20 m apartment block in Aizawl
Mizoram, residential, between 15 m and 35 m.
What applies Mizoram's own row in the 2026 Third Schedule drops the down-comer and asks for a 5,000 litre terrace tank and a 450 litre a minute pump. Above 35 m it asks for a wet riser and a 20,000 litre underground tank. Mizoram Home Dept
Case 3
A 300 m² godown near Imphal
Manipur, storage under 15 m, ground floor only.
What applies A wet riser and a yard hydrant, a 50,000 litre underground and a 10,000 litre terrace tank, and electric and diesel pumps of 1,620 litres a minute with a 180 litre pump. Government of Manipur
Case 4
A ground plus 2 nursing home in Delhi
Institutional, under 15 m.
What applies The Delhi Fire Service nursing-home sheet asks for a 75,000 to 1,50,000 litre underground tank, 1,620 litre a minute pumps, a 10,000 litre terrace tank and a 180 litre a minute jockey pump. DFS
Case 5
Any building with risers in Goa
Any occupancy the Directorate inspects.
What applies Goa's checklist asks for wet risers or down-comers of 100 mm and landing valves of 63 mm, matching the national sizes. Directorate of Fire and Emergency Services, Goa
Case 6
A 26 m hotel under construction in Agartala
Tripura, a high-rise at 24 m or more.
What applies While it is being built: a 100 mm dry riser, 2,000 litre drums on each floor and a 20,000 litre tank. Directorate of Fire and Emergency Services, Tripura
Case 7
A multi-storey building in Jaipur
Rajasthan, under the Model Building Regulations, 2025.
What applies Two rooftop tanks: one connected to the fire-fighting pipes, the other fed from 30 cm below the fire tank's lid, so the fire tank stays full. Rajasthan UDH

Wet riser standards: which IS editions are current

Read on the BIS standards database on 24 October 2026. Several sites still cite older editions.

Current
IS 3844:1989
Internal fire hydrants and hose reels, installation and maintenance. Published 31 May 1990, valid to 20 June 2030. BIS standards database
Current
IS 9668:1990
Provision and maintenance of water supplies for firefighting. Published 30 September 1990. BIS standards database
Current
IS 13039:2014
External hydrant systems, provision and maintenance. Published 30 June 2014. BIS standards database
Current
IS 15301:2003
Installation and maintenance of fire pumps. Published 30 April 2003, valid to 31 August 2028. BIS standards database
Revised 2025
IS 5290:2025
Landing valves, fourth revision, published 19 March 2025. IS 5290:1993 was withdrawn on 10 September 2025. BIS standards database
Revised 2025
IS 884:2025
First-aid hose reel, second revision, published 26 March 2025. BIS standards database
Current
IS 636:2018
Non-percolating fire delivery hose, fourth revision, published 31 December 2018. BIS standards database

Wet riser rules in India, 1983 to 2026

1983 and 1997
The 1983 NBC fire chapter is modified in 1997 by Amendment No. 3, which changes the wet riser and down-comer requirements. BIS, SP 7:2026
31 May 1990
IS 3844:1989, the code for internal hydrants and hose reels, is published. It is still the current edition. BIS standards database
2016
NBC 2016 Table 7 puts a down-comer in flats of 15 m to 35 m and a wet riser above 35 m. NBC 2016, Part 4
19 March 2025
IS 5290:2025, the fourth revision of the landing valve standard, is published; the 1993 edition is withdrawn on 10 September 2025. BIS standards database
30 April 2026
NBCS 2026 replaces NBC 2016; the one Table 7 becomes Tables 7A to 7J with protection levels, and Tables 7K and 7M for water. Gazette of India
2 June 2026
Tripura's Fire Safety Rules, 2026 write the NBCS wet riser definition into state law. Directorate of Fire and Emergency Services, Tripura
7 July 2026
Maharashtra's Form B guidelines require one agency to maintain a building's pumps, hydrants and sprinklers. MFS Form B guidelines
20 August 2026
Mizoram's amendment sets its own riser rows and the 30 m hose-reach rule. Mizoram Home Dept

Wet riser faults that fail a fire inspection

Each of these breaks a named clause, and each is easy to see on a site visit.

If The ground-floor hydrants blow above 7 bar
Fit orifice plates or pressure-controlled hydrant valves, or zone the riser, so every outlet sits between 3.5 and 7 bar. BIS, SP 7:2026
If The domestic pump draws from the fire tank
Feed the domestic suction only from the fire tank's overflow, or set its inlet above the fire reserve. BIS, SP 7:2026
If Riser valves are shut, or open with nothing to stop someone closing them
Wire a supervisory switch to the fire alarm panel, or chain and padlock each valve open with a serial-numbered tamper-proof tag. BIS, SP 7:2026
If One single fire tank with no partition
Divide it into two or more equal, interconnected compartments so cleaning never empties the reserve. BIS, SP 7:2026
If A down-comer spits air when charged
Fit the air release valve at roof level that the down-comer definition requires. BIS, SP 7:2026
If The pump room is in the third basement, or uses submersible pumps
Move it to ground level or the first or second basement; submersible and negative-suction pumps are not allowed. BIS, SP 7:2026
If In Maharashtra, two agencies maintain the pumps and the hydrants
Give pumps, hydrants, sprinklers and other water systems to one licensed agency for the whole building. MFS Form B guidelines

Wet riser maintenance and Form B checklist

What to check, and what Maharashtra asks a licensed agency to prove, twice a year.

Pressure of at least 3.5 bar at the topmost landing valve, and no more than 7 bar at the lowest BIS, SP 7:2026
A dated photo of the main hydrant pump's gauge with the topmost hydrant and hose reel open, for Maharashtra Form B MFS Form B guidelines
Form B filed by the licensed agency in January and in July MFS Form B guidelines
Every riser and ring valve open, supervised or padlocked with its serial-numbered tag BIS, SP 7:2026
Both tank compartments full to the fire reserve, manholes clear for suction hoses BIS, SP 7:2026
Electric pump, standby pump and jockey pump all present and starting BIS, SP 7:2026
Hose reels of at least 19 mm on every required floor, connected to the riser BIS, SP 7:2026
Where a dry riser replaced the wet riser, a quarterly check of flow and pressure BIS, SP 7:2026

Five wet riser myths

You may have read
A wet riser is fed by gravity from the roof tank.
Myth
What the sources say
That is a down-comer. A wet riser is charged from a pressurised supply, the building's pumps (clauses 2.10 and 2.70). BIS, SP 7:2026
You may have read
A dry riser is a cheaper wet riser anyone may choose.
Myth
What the sources say
NBCS 2026 allows the swap only up to 24 m with a public hydrant main giving full flow 24 hours a day, or below 4 °C. NBC 2016 note 24 limits it to hilly or industrial areas, or where the local authority asks. BIS, SP 7:2026
You may have read
NBCS 2026 made wet risers optional because the standard is voluntary.
Myth
What the sources say
The standard is voluntary, but your state's rules decide, and many still follow NBC 2016 Table 7. Only Assam had written NBCS 2026 into its fire law by 24 October 2026. NBC 2016, Part 4
You may have read
A tall block needs both a down-comer and a wet riser.
Myth
What the sources say
The codes give one or the other: NBC 2016 switches flats from a down-comer to a wet riser above 35 m, and NBCS 2026 marks the down-comer not required where it asks for a wet riser. NBC 2016, Part 4
You may have read
The hose reel runs on its own pipe.
Myth
What the sources say
NBCS 2026 connects the first-aid hose reel directly to the riser or down-comer main, with hose of at least 19 mm. BIS, SP 7:2026

Wet riser choices for builders and housing societies

Do

Ask the fire service in writing whether it reads your plans against NBC 2016 Table 7 litres or NBCS 2026 protection levels. Gazette of India
Use 150 mm mains where Table 8 asks for them, such as hotels, hospitals and offices above 15 m. BIS, SP 7:2026
Keep a pump set for every 100 hydrants, at most two sets, with their delivery headers joined. NBC 2016, Part 4

Don’t

Don't cut a 20 m block's terrace tank to 5,000 litres outside Mizoram: NBC 2016 asks for 25,000 for 15 m to 35 m. NBC 2016, Part 4
Don't fit pumps that shut off above 12 bar in a tower over 60 m; zone the system instead. BIS, SP 7:2026
Don't store anything else in the fire pump room: no other utility equipment is allowed there. BIS, SP 7:2026

What Flamekite could not confirm about wet risers

Four gaps a reader should know about before relying on any single number on this page.

NBCS 2026 Table 7A no longer prints tank sizes in litres. Table 7M gives flows instead: level HL-3 is 4 hose streams of 270 litres a minute, or 1,080 litres a minute. At the 30 to 60 minutes the table allows, that is 32,400 to 64,800 litres. That is Flamekite's arithmetic, not a BIS figure.

Table 7M's own worked example does not add up. It takes 1,080 litres plus 40% to get 1,512, then divides by 140% and prints 1,514 lpm, but 1,512 divided by 1.4 is 1,080. The 1,514 lpm pump matches 1,512 rounded up to a standard pump. Table 7K's example, by contrast, does divide by 1.4.

The apartment row in Table 7A groups towers of 24 m to 60 m with buildings under 24 m, then gives only floor-area bands. How a 30 m tower with 800 m² floors is classed is not stated. Ask your fire service before you design.

IS 3844:1989 has been read and is summarised on its own page: hydrants within 30 m of any point they cover, rising mains at most 50 m apart, a 700 kPa test for 30 minutes before use. Haryana's 2022 Act, read for Flamekite's Haryana page, has no riser or tank table.

Wet riser questions people ask

What is a wet riser?: A wet riser is a vertical fire main of at least 100 mm, kept permanently full of water under pressure by the building's fire pumps, with a landing valve on every floor. Firefighters connect their hoses to it instead of laying hose up the stairs. NBCS 2026 Part F defines it in clause 2.70.
What is the difference between a wet riser and a dry riser?: A wet riser is always full of water under pressure from the building's pumps. A dry riser stays empty until a fire engine pumps water in through an inlet at ground level, so water reaches the floors later. NBCS 2026 allows a dry riser instead only up to 24 m with a reliable public hydrant main, or in very cold places.
What is a downcomer in fire fighting?: A down-comer is a fire main of at least 100 mm fed from the terrace tank by a terrace pump, with a landing valve on each floor, a ground-level inlet for fire engines and an air release valve at the roof. NBC 2016 uses it in flats of 15 m to 35 m.
What size is a wet riser pipe?: At least 100 mm. Table 8 of NBCS 2026 Part F sets 100 mm with a 63 mm landing valve for most buildings up to 15 m, and 150 mm for hotels, institutional and business buildings above 15 m and for industrial, storage and hazardous buildings up to 15 m.
What pressure should a wet riser give?: At least 3.5 bar at the highest and the hydraulically remotest hydrant, and no more than 7 bar at any hydrant, so the hose stays safe to hold. Lower floors use orifice plates or pressure-controlled valves to stay under the limit.
Which IS code covers wet risers?: IS 3844:1989, the code of practice for internal fire hydrants and hose reels, which is still the current edition on the BIS database. Water supplies follow IS 9668:1990, fire pumps IS 15301:2003 and landing valves IS 5290:2025.
From what height is a wet riser compulsory?: It depends on your state's rules. Under NBC 2016 Table 7, flats and hostels need a down-comer from 15 m and a wet riser above 35 m. Under NBCS 2026 the trigger is floor area as well as height: apartments of 1,001 m² and above get a wet riser.
How big should the fire tank be for a wet riser?: NBC 2016 sets 75,000 litres underground for flats above 35 m, 1,50,000 above 45 m and 2,00,000 above 60 m, plus a terrace tank. NBCS 2026 works it out from flow and a duration of 30 to 120 minutes instead of printing litres.

Keep reading

Fire hydrant system MCQWet riser, pump and hose reel questions with cited answers.
Fire safety glossaryEvery fire-law term, defined from the act, rule or code that uses it.
Fire loadThe heat a room's contents can release, and how it sets the hazard class and pump size.
National Building Code 2026What changed when NBC 2016 was withdrawn, and which edition your state uses.
Fire NOC in MaharashtraForm B every January and July from a licensed agency.
Fire NOC in ManipurSchedule I risers, tanks and pumps by building type.
Fire NOC in MizoramThe 2026 amendment and its own Third Schedule.
Fire NOC checkerCheck whether your building needs a fire NOC in your state.

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Wet riser at a glance

Wet riser vs dry riser vs down-comer

How a wet riser is sized and approved, step by step

Fix the occupancy and the height

Read which riser the row asks for

Size the flow and the pumps

Size the mains and zone the riser

Size the tank

Show it on the fire NOC drawings

Keep it certified