IS 14399 Explained: What the BIS Standard Demands from an SMC Panel Tank

Almost every SMC panel tank quotation in India carries the same reassuring words: “BIS quality”, “ISI standard”, “as per IS norms”. Very few carry the one number that actually decides whether the tank is compliant – IS 14399.

IS 14399 (Parts 1 and 2): 1996 is the Indian Standard for Hot Press Moulded Thermosetting Glass Fibre Reinforced Polyester Resin (GRP) Sectional Water Storage Tanks. It was published in December 1996 by the Sanitary Appliances and Water Fittings Sectional Committee (CED 3) and reaffirmed in 2008. If you are buying, specifying or approving a sectional panel tank for potable water in India, this is the document your specification should point to – and the document your supplier should be able to discuss clause by clause. The full text is public on the BIS standards repository.

This guide breaks down what the standard actually demands – from resin chemistry and panel thickness to hydrostatic pressure, potability and the 48-hour leakage test on the assembled tank – and how a buyer can verify compliance before releasing a purchase order.

IS 14399 at a Glance

Item	Detail
Standard number	IS 14399 (Parts 1 and 2): 1996
Full title	Hot Press Moulded Thermosetting Glass Fibre Reinforced Polyester Resin (GRP) Sectional Water Storage Tanks
Part 1	Specification for panels
Part 2	Guidelines for assembly, installation and testing
Committee	Sanitary Appliances and Water Fittings Sectional Committee, CED 3
Status	Published December 1996; reaffirmed 2008; Part 1 carries Amendment No. 1 (June 2003)
Moulding process	Hot compression moulding using Sheet Moulding Compound (SMC)
BIS certification	A single combined licence is granted covering both Part 1 and Part 2

What Is IS 14399?

IS 14399 is written in two linked parts, and the distinction matters commercially because a supplier can be strong on one and weak on the other.

· Part 1 – Specification for panels. It governs the raw materials, colour, panel dimensions and flanges, visual quality, six mechanical and physical properties, the hydrostatic test, the deflection test, the potability type test, sampling rules and marking.

· Part 2 – Guidelines for assembly, installation and testing. It governs sealants, bolts and nuts, the support system, roof, connections, manhole hatches, air vents, ladders, tank dimensions, the assembly arrangement, the foundation and the leakage test on the completed tank.

The BIS product manual for this standard confirms that, as per existing practice, “combined licence is granted for both parts” – so a genuine licensee is certified for the panel and the erected tank, not just one of them. The manual is published at bis.gov.in.

Does IS 14399 Apply to SMC Panel Tanks?

Yes – and the standard says so explicitly, which surprises many buyers who assume GRP and SMC are two different products from two different standards.

Clause 1.1.1 of Part 1 states that the GRP panels covered by the standard are hot compression moulded using sheet moulding compound (SMC). Clause 3.3 then defines SMC as a hot compression mouldable compound based on polyester, fibreglass, fillers and high-temperature catalysts, chemically pre-thickened into a non-tacky sheet form.

So the relationship is simple:

· SMC is the moulding compound – the raw sheet that goes into the press.

· GRP is what the finished panel is – glass fibre reinforced polyester.

· The panel is produced by hot compression moulding, not hand lay-up or spray-up.

This is why the technically correct phrase in a tender is “SMC panel tank conforming to IS 14399 (Parts 1 and 2): 1996”, not “BIS-certified SMC tank”. The first can be verified against a licence; the second cannot. If you want the underlying chemistry in more detail, our explainer on what actually goes into a panel covers the resin-and-glass composite in plain language.

Material Requirements Under IS 14399

Unsaturated Polyester Resin

Clause 4.1 requires food-grade unsaturated thermosetting polyester resin reinforced with glass fibre, with catalysts and optionally pigments and UV stabilisers. The resin system must conform to IS 6746 and meet defined characteristics, including a specific gravity of 1.13 +/- 0.01 at 27 degrees C, acid value of 16 +/- 4 mg KOH/g, volatile content of 30 +/- 3 percent and a gel time of 20 to 30 minutes at 25 degrees C.

The cured resin has its own acceptance criteria – minimum 40 BHU Barcol hardness, elongation at break of 1.9 percent within tolerance, and maximum 1 percent water absorption after 7 days at 25 degrees C. There is also a hydrolysis test in which cured samples roughly 50 mm x 50 mm x 3 mm are boiled in distilled water at 100 degrees C for 200 hours, weighed, boiled a further 200 hours and re-weighed. There must be no evidence of weight loss from polymer breakdown.

Glass Fibre Reinforcement

Clause 4.3 requires commercial grade E-type glass fibre conforming to IS 11273, IS 11320 or IS 11551 as appropriate. Amendment No. 1 of June 2003 added a hard floor to the compound itself: the minimum glass content in the compound shall be 30 percent by weight. This single amendment is one of the quickest ways to separate a serious manufacturer from a filler-heavy panel.

Fillers and Additives

Only inert inorganic fillers with particle size below 0.05 mm are permitted, and only if required. Additives may be used to modify resin properties. Nothing in the formulation may compromise the water.

Potable Water Safety

Clause 4.1 is unusually direct: materials in contact – or likely to come into contact – with water must not constitute a toxic hazard, must not support microbial growth, and must not give rise to unpleasant taste or odour, cloudiness or discolouration of water. The standard also places a duty on the tank manufacturer to obtain a certificate to this effect from the raw material manufacturer. That certificate is a fair thing to ask for during technical scrutiny.

Panel Thickness, Sizes and Tolerances

Panels are classified by type, and each type carries a minimum thickness under Clause 6.4.

Panel type	Minimum thickness	Typical location in the tank
Type A	3 mm	Top, and upper tiers of the sides
Type B	4 mm	Middle tier of the sides in deeper tanks
Type C	5 mm	Bottom and lowest tier of the sides

Half and quarter panels of any type must carry the corresponding minimum thickness – a common shortcut area, because smaller panels around inlets, outlets and drains are sometimes moulded thinner than the full panels beside them.

The standard also fixes dimensional discipline:

· Nominal external unit panel sizes of 1 m x 1 m, 1 m x 0.5 m or 0.5 m x 0.5 m, or another size mutually agreed between purchaser and manufacturer.

· Tolerance within +/- 0.2 percent of external dimensions, and angular tolerance within +/- 0.3 degrees.

· Flanges formed as a combined double flange at 45 degrees and 90 degrees, or a single flange at 90 degrees, with bolt holes positioned according to where the panel sits in the tank.

· Joint width (land width) of the flange not less than 45 mm.

· Panel colour in a shade of grey or cream, unless another pastel shade is mutually agreed.

Clause 7 adds a visual acceptance gate. Internal and external surfaces must be free from pits, poor impregnation of fibreglass with resin, cuts, cracks and scratches exposing the glass, sharp projections or exposed fibres, surface repair marks, and blisters caused by air pockets.

The Six Panel Properties That Decide Compliance

Clause 8 and Table 1 of Part 1 set the acceptance criteria that a panel must meet, tested on specimens cut from panels or from flat laminates made in the same composition and by the same technique. These are the numbers worth writing into a specification.

Property	Acceptance criteria	Test method
Tensile strength	70 MPa (minimum)	Annex B
Bending strength (cross-breaking)	100 MPa (minimum)	Annex C
Elastic modulus in bend	6,000 MPa (minimum)	Annex D
Glass content	25 percent (minimum)	Annex E
Barcol hardness	50 BHU (minimum)	Annex F
Water absorption	0.5 percent (maximum)	Annex G

Read these together, not one at a time. Tensile and bending strength describe how much load the laminate can take; elastic modulus describes how stiff it stays; glass content explains why; Barcol hardness indicates cure quality; and water absorption predicts how the panel behaves after years submerged. A panel that is thick but under-cured will pass a vernier caliper and fail the standard. That relationship between composition and service life is explored further in our note on why material strength governs tank durability.

Hydrostatic and Deflection Testing

Clause 9 requires panels fixed to a hydrostatic tester to withstand a defined pressure without bursting, cracking or leakage. Crucially, the pressure is tied to the panel type – which is in turn tied to where the panel sits and how deep the tank is.

Panel type	Hydrostatic pressure to be withstood
Type A	0.04 MPa
Type B	0.08 MPa
Type C	0.12 MPa

The deflection test under Clause 10 runs simultaneously with the hydrostatic test. Maximum deflection at the centre of the panel must not exceed 10 mm, measured with a dial gauge graduated to 0.01 mm with a range of at least 25 mm. The gauge is zeroed, the panel is pressurised, a reading is taken immediately on reaching working pressure, the pressure is held for 4 hours, a second reading is taken at the same position, and the greater of the two results is used. That four-hour hold is what separates a real test report from a convenient one.

The Potability Type Test

Clause 11 exists for one reason: the panel must not contaminate the water it stores. It is conducted as a type test and covers four distinct areas.

· Taste, odour, colour and turbidity – assessed on the seventh extract, which must show no deterioration in colour or turbidity against the original tap water, and must not carry a taste or odour described as chlor-phenolic, medicinal or disinfectant.

· Toxic metals – the amounts in the extract must not exceed the limits specified in IS 10500, the Indian Standard for drinking water.

· Cytotoxicity – the extract after the third extraction must be free from cytotoxicity.

· Microbiological growth – counts taken 4, 5 and 6 weeks after inoculation, assessed against the control flask and against absolute limits.

The absolute limits below which the count is acceptable are specified in Table 2 of Part 1:

Organism	Maximum limit
Coliform organisms	0 per 100 ml
Pseudomonas aeruginosa	0 per 100 ml
Colony count at 37 degrees C	100 per ml
Colony count at 22 degrees C	10,000 per ml
Fungi	100 per ml

The standard requires this test to be repeated whenever a significant change is made in the composition or process. The BIS product manual goes further for licensees: if a sample fails the type test, marking must be stopped under intimation to BIS and may only resume after corrective action is verified and an improved sample passes. This is the clause that gives real meaning to the hygiene claims discussed in our article on keeping stored water safe in a sectional tank.

What Part 2 Demands from the Complete Tank

A compliant panel does not make a compliant tank. Part 2 covers everything that happens after the panels leave the press.

Sealants, Bolts and Fasteners

· Sealing material must be non-toxic, chemically resistant to the stored water and able to withstand service temperature variation. Butyl rubber, neoprene rubber or silicone rubber sealants are recommended; anything else needs the purchasing authority’s approval.

· Bolts and nuts must conform to IS 1364 (Part 1) and IS 1364 (Part 3), with bolt diameter not less than 10 mm, hot dip galvanised to IS 1367 (Part 13).

· Where internal bolting is used, the bolts must be stainless steel.

Support System and Foundation

· Interior supports must be stainless steel conforming to IS 6911, or GRP, or UPVC.

· Exterior supports must be mild steel thoroughly coated with a suitable non-corrosive, non-toxic material, or hot dip galvanised to IS 1367 (Part 13).

· The foundation and support system must be designed for the worst loading combination, and a crossed girder system in structural steel giving peripheral support to every bottom panel is recommended – with the edge of every panel resting on the steel structure.

That last line is the single most violated requirement on Indian sites. A tank erected on an uneven plinth or on beams spaced to suit the slab rather than the panel grid will leak at the joints long before the laminate fails, whatever the test certificate says. Our site erection walkthrough shows how the base grid is set out in practice, and the terrace-specific guide covers load transfer on rooftops.

Roof, Manhole, Vents, Ladders and Connections

· The roof must be of non-corrosive material with sufficient strength to allow man traffic.

· Manhole hatches must be of GRP with hinges of aluminium alloy or stainless steel, and the minimum internal diameter of the manhole must not be less than 450 mm.

· Air vents must be of GRP or PVC, designed to prevent the entry of insects and other foreign material.

· Internal ladders must be of aluminium alloy or GRP; external ladders may be mild steel, fully coated.

· Inlet, outlet, overflow, drain and vent – their sizes, materials and positions are to be agreed between the purchaser and the supplier, which means they belong in your purchase order, not in a post-delivery conversation.

Tank Dimensions and the Depth-to-Panel Rule

Length and breadth are specified in multiples of 0.5 m or 1 m, and depth in multiples of 0.5 m. Table 1 of Part 2 then sets the assembly arrangement, and this is where panel type stops being a catalogue option and becomes an engineering requirement.

Depth of tank	Panel location	Panel type
1 m	Top, bottom and sides	A
2 m	Bottom and lower tier of sides	B
	Top and top tier of sides	A
3 m	Bottom and lowest tier of sides	C
	Middle tier of sides	B
	Top and top tier of sides	A

This table is the reason two tanks of identical litreage can be priced very differently and both be described as “IS 14399”. A shallow, wide tank built from Type A panels and a deep tank requiring Type C at the base are not the same product. Before comparing quotations, fix the footprint and depth first – our capacity planning guide explains how to arrive at those numbers for a building.

Leakage Test

Clause 7 of Part 2 is refreshingly unambiguous. After assembly, the tank is filled with water up to the overflow level, and after 48 hours there shall be no visible sign of leakage. If the initial test fails, the leaks are stopped in accordance with the manufacturer’s recommendations and a further test is carried out. In the BIS scheme of inspection, the leakage test applies to each tank, and a record of each installation must be maintained.

How to Verify an IS 14399-Compliant SMC Panel Tank

The BIS product manual sets out exactly how a licence is worded, which gives buyers a precise checklist. The scope of licence names the product, the type of panel (A, B or C) and the depth range covered, stated as “from __ m up to and including __ m”. Production that conforms and is covered by the licence should carry the Standard Mark.

Use this at the technical-scrutiny stage:

· Ask for the BIS licence number and see the licence itself, not a photocopied logo.

· Check the product name on the licence – it should read as hot press moulded thermosetting GRP sectional water storage tanks.

· Confirm the licence covers Part 1 and Part 2, since the combined licence is the normal practice.

· Check which panel types are in scope. A licence covering Type C also covers B and A, because the thickest tested panel governs – but a Type A licence does not cover a Type C requirement.

· Check the licensed depth range against your tank depth. Testing is grouped by depth bands: up to and including 1 m, above 1 m up to 2 m, and above 2 m up to 3 m.

·  Ask for recent test reports covering the six Table 1 properties, plus hydrostatic and deflection.

·  Ask for the potability type test report and the raw material manufacturer’s certificate.

·  Confirm marking on the panels – source of manufacture, type and thickness of panel, and lot or serial number are all required by Clause 13.

·  Ask for the leakage test record and the installation record for the completed tank.

Claims That Deserve a Second Question

· “BIS approved” with no licence number and no scope.

· An IS 14399 claim for a product that is not a hot press moulded GRP sectional tank.

· Panel thickness quoted with no mechanical test data behind it.

· A compliance claim resting on the word fibreglass alone.

· A panel test certificate offered as proof that the installed tank is compliant.

· No mention of panel type against tank depth in the technical offer.

· No potability evidence where the tank will store drinking water.

· No leakage test protocol or handover record in the scope of supply.

IS 14399 vs a Generic “SMC Tank” Specification

Factor	Generic SMC tank claim	IS 14399-based specification
Material	“SMC” named, nothing more	Food-grade unsaturated polyester with E-glass to referenced IS standards
Panel thickness	A number in the brochure	Type A/B/C linked to minimum thickness and to tank depth
Strength	“High strength”	70 MPa tensile, 100 MPa bending, 6,000 MPa modulus, minimum
Pressure	Not stated	0.04 / 0.08 / 0.12 MPa by panel type, with 10 mm deflection limit
Drinking water	“Food grade”	Type test covering taste, odour, turbidity, toxic metals, cytotoxicity, microbes
Installation	Vendor practice	Defined sealants, fasteners, supports, foundation and 48-hour leakage test
Certification	“BIS quality”	Licence number, panel types and licensed depth range, with Standard Mark

For a project owner, the practical value of naming IS 14399 in the tender is that every one of those right-hand entries becomes a verifiable, arguable contract term. Where the tank also serves fire reserve duty, the volume itself is governed separately – our guide to fire water storage requirements under the National Building Code covers that side of the specification, and a comparison of sectional, overhead and RCC construction helps at the concept stage.

Frequently Asked Questions

1. Is IS 14399 the same as IS 12701?

No. IS 12701 covers rotationally moulded polyethylene water storage tanks – the seamless plastic tanks commonly seen on residential terraces. IS 14399 covers hot press moulded GRP sectional tanks assembled from panels. Quoting IS 12701 in a panel tank tender, which happens more often than it should, makes the specification unenforceable.

2. Is there a capacity limit to the tanks IS 14399 covers?

Part 2 states its scope as GRP sectional water storage tanks of capacities from 1,000 litres to 5 lakh litres. Requirements beyond that range, or beyond the maximum depth the standard addresses, move into project-specific structural engineering, and the design basis should be agreed in writing with the manufacturer rather than assumed to be covered.

3. Can an IS 14399 tank be used for hot water or industrial process liquids?

The scope of both parts is limited to potable water at a temperature not exceeding 50 degrees C, and at pressure not exceeding the static head corresponding to the depth of the tank. Hot water, chemicals, effluent or pressurised service are outside the standard’s scope, and a compliance claim made for those duties is being stretched beyond what the certificate supports.

4. How often must a BIS licensee retest its panels?

Under the BIS scheme of inspection and testing, a control unit is 300 water tank panels or part thereof, of the same type, from the same batch of raw material and machine. Routine tests are performed per control unit, visual inspection applies to every panel, and the potability type test must be repeated once in three years even when nothing in the composition or process has changed. Asking for the date of the last type test is a quick way to gauge how live a licence is.

A Note on Verification

The clause references and values in this article are drawn from IS 14399 (Parts 1 and 2): 1996 and the BIS Product Manual for IS 14399 (May 2020). Standards are amended and licences change scope. Before procurement, confirm the current BIS document, verify the supplier’s licence scope directly, and have the tank depth, foundation and loading checked against your project’s structural requirements.