What are the standard capacities for plastic flushing cisterns?

Commonly 10 litres for single flush, and 6/3 litres for dual flush models. Other capacities like 5 litres are also permitted if they meet performance tests (Clause 6.1).

What material is specified for the cistern body?

The body and cover must be made from suitable thermoplastics like High-Density Polyethylene (HDPE) or Polypropylene (PP) (Clause 4.1).

What is the durability requirement for the flushing mechanism?

The operating mechanism must withstand an endurance test of 50,000 flushing cycles without failure (Clause 7.2).

Is leakage allowed from the cistern?

After being filled and left for one hour, the leakage from the cistern outlet shall not exceed 50 ml (Clause 8.4).

IS 7231

: 1994

plastic flushing cisterns for water closets and urinals

CurrentFrequently UsedSpecificationBIMMEP · Sanitary Appliances and Water Fittings

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This standard specifies the requirements for materials, construction, dimensions, and performance of plastic flushing cisterns, including single and dual-flush models, for use with water closets and urinals. It outlines tests for flushing effectiveness, leakage, and mechanical endurance to ensure product quality and water conservation.

plastic flushing cisterns for water closets and urinals

Quick Reference Values

Nominal capacity (single flush)10 litres

Nominal capacity (dual flush - full/half)6/3 litres

Minimum wall thickness of cistern body2.5 mm

Endurance test for operating mechanism50000 cycles

Maximum permissible leakage after 1 hour50 ml

Minimum flow rate for float operated valve0.15 l/s at 0.05 MPa

Practical Notes

Always check for the ISI mark on the product, which certifies compliance with material, performance, and safety standards.

Ensure the float valve (ballcock) assembly also complies with IS 1703 for reliable water filling and shut-off.

For dual-flush cisterns, verify both full-flush and half-flush volumes are correctly set up on-site to achieve intended water savings.