Plumbing Points Estimator

How this estimator works

1. Bathroom = 9 points: WC inlet, health faucet, basin hot and cold, shower mixer hot and cold, shower outlet, floor trap and a spare for a future bidet or washing machine.
2. Kitchen = 5 points: sink hot and cold, waste, water purifier feed and a dishwasher or washing-machine cock.
3. Utility = 3 points: washing-machine inlet, waste and a floor trap.
4. Cost = points × pipe system rate × concealment factor, plus geyser points at ₹4,200 each and chasing at ₹320 per point where the walls are existing.
5. Rates are installed — pipe, fittings, clamps, labour and testing — but not the fixtures themselves.

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Worked example — a standard 2BHK

The rules that prevent a leak behind tile

Pressure test before closing. Every concealed line gets charged to 6 bar and held for two hours with the gauge visible, and somebody photographs the start and end reading. A joint that weeps a drop an hour is invisible on the day and shows as a damp patch on the neighbour's ceiling eight months later, by which time the tile has been laid over it and the repair costs twenty times the test.

Second, keep concealed joints to a minimum and never put one behind a fixed fitting. Run continuous lengths wherever possible and place any unavoidable joint where an inspection panel or a removable vanity gives access. A CPVC solvent joint properly made is extremely reliable; the failures we see are almost always a joint made in a hurry in a cramped chase.

Third, respect the slope on waste lines. A 110 mm soil line needs a fall of at least 1 in 60 and a 40 mm waste 1 in 40. In a Mumbai flat with a shallow sunken slab there is often only just enough depth to achieve it, and an inspector's tape on the finished screed is worth more than a contractor's assurance. A waste line laid flat will block, repeatedly, for the life of the bathroom.

One more thing to specify in writing: isolation valves. Every bathroom and the kitchen should have its own isolating valve on the incoming line, so that a leak or a tap change ten years from now does not mean shutting off the whole flat. Angle valves at each fixture do the same job at fixture level. Between them they cost a few thousand rupees during the project and save a plumber cutting into a wall on a Sunday afternoon.

Plumbing sits outside the audited residential rate card, which excludes plumbing and sanitary work altogether, so the point rates here are our own current Mumbai pricing for pipework rather than a figure reconciled against completed-project billing. They move with copper and CPVC prices, so treat them as current rather than fixed. Treat the output as a planning figure: accurate enough to brief a landlord, a bank or a family, and not accurate enough to sign a contract against.

What this tool does not cover

• Sanitaryware, taps, mixers, showers and the geyser itself.
• Soil and waste stack modification, which in an apartment usually needs society permission and coordination with the flats above and below.
• Waterproofing, which follows the plumbing — see the waterproofing area calculator.
• Water tanks, pumps, filtration and softeners.
• Drainage surveys and camera inspection of existing lines, which are worth doing in any building over 25 years old.
• For the electrical side of the same rooms, see the electrical points estimator.

Selected work by Greenbox Design Studio. Tap any image to enlarge.