"Water positive" homes: what the claim would need to be true

Some projects say they are "water positive", sometimes with a percentage. For a family worried about water, that sounds wonderful. But there is no single legal definition behind the phrase. Here is what a fair version of it would need.

Three things any water claim needs

1. A boundary: what area and which uses are counted.
2. A baseline: what the project is being compared against.
3. A meter: real readings, over time, after people live there.

Without all three, a percentage is just a number.

How the boundary can flatter the result

If a claim counts only the garden, or leaves out tanker water, or ignores construction use, the figure can look far better than reality. Ask what is in, and what is out.

Three different ways to help

• Reduce: fittings that use less water.
• Reuse: treated STP water for flushing and gardens.
• Recharge: sending rain into the ground.

All three are good. They are not the same thing, and adding them into one number can hide which is doing the work.

A design figure is a forecast

Before a building is occupied, any water figure comes from a model. It is a forecast. Real use depends on how residents live and how well the systems are run.

What you can honestly expect to see

At design stage, a builder can honestly show you features, not results: the rainwater harvesting plan, the STP and dual plumbing, the fittings and their flow rates, and meters that let the residents track use later.

Questions to ask

• What is counted in this claim, and what is left out?
• Is it a design forecast or a measured result?
• Which features are in my agreement?
• Will there be water meters for the residents to track use?

Why water deserves its own questions

For many families, water is the biggest everyday worry in a new home. Where it comes from, whether it is enough in summer and what it costs if tankers are needed all decide how comfortable life is. A slogan does not answer any of that. A clear plan does.

A worked example: simple rainwater arithmetic

Here is how to sense-check a rainwater claim with plain arithmetic. One millimetre of rain on one square metre of roof is one litre of water. Take an illustrative terrace of 1,000 square metres and a year with 900 mm of rain. The rain that falls on that terrace is 1,000 × 900 = 9,00,000 litres. Not all of it can be caught: some evaporates, splashes or overflows, so designers apply a collection factor. At an illustrative 0.8, that is about 7,20,000 litres a year.

Now compare that with use. If 54 households each used an illustrative 500 litres a day, that is 27,000 litres a day, or about 98.5 lakh litres a year. On these example numbers, roof rainwater alone would meet well under a tenth of yearly use. That does not make rainwater harvesting unimportant. It shows why any big percentage needs a clear boundary and baseline, and why reuse and lower use matter just as much.

Use your own figures for the roof area, rainfall and the number of homes. The method is the point: area × rainfall × collection factor, compared with daily use × 365.

Step by step: checking a project's water plan

1. Source. Ask where water will come from after handover: a municipal connection, borewells, tankers or a mix.
2. Storage. Ask the size of the underground and overhead tanks, in litres, and divide by the number of homes.
3. Treatment. Ask whether there is a water treatment plant for borewell water, and an STP for wastewater.
4. Reuse. Ask whether treated STP water goes to flushing through separate pipes, and to the garden.
5. Recharge. Ask how many recharge pits or wells are planned, and where.
6. Metering. Ask whether each home will have its own water meter. Metering lets residents see use and share costs fairly.
7. Agreement. Check which of these features appear in the agreement for sale or its specification list.

Common mistakes

• Trusting a percentage with no boundary. Always ask what is counted.
• Confusing harvesting with supply. Recharging the ground is good, but it is not the same as water in your tap.
• Ignoring the running cost. STPs and treatment plants need power, chemicals and an operator. Residents usually pay for these through maintenance.
• Not asking about summer. Ask what happens in April and May, when supply is lowest.
• Relying on the brochure. A feature in your agreement is a promise you can hold the builder to. A brochure line is far weaker.

Your water checklist

• Source after handover, in writing.
• Storage per home, in litres.
• STP and dual plumbing confirmed.
• Rainwater harvesting seen on the plan.
• Individual water meters.
• Features listed in the agreement.
• Expected running costs in the maintenance estimate.

What a fair answer sounds like

A builder who has planned water well can usually answer in plain numbers and places. For example: "Our underground tank holds this many litres. Treated STP water goes to all flushing through a separate line. There are this many recharge pits, shown here on the site plan. Each flat has its own meter." You can check every part of that on the plan and on site. Compare that with an answer that only repeats a percentage, or talks about being eco-friendly without numbers. The first gives you something to verify; the second gives you nothing.

Water and your monthly budget

Water cost shows up in two places: your own bill if the home is metered, and the shared maintenance charge that pays for pumping, treatment and tankers. A well-planned system with reuse and lower-flow fittings can reduce what the building needs to buy in. That is why the questions above are not just about the environment. They are about what you will pay every month for as long as you live there.

After you move in

Once residents take over, keep an eye on the systems. Ask the association to share monthly water use from the meters, and to check that the STP is running and treated water is reaching the flush lines. A system that works on paper only helps if it is run well.

A short glossary

• Boundary: the area and the uses included in a water calculation.
• Baseline: the typical use a project compares itself against.
• Recharge pit: a pit that lets rainwater soak into the ground.
• STP: sewage treatment plant, which cleans wastewater for reuse.
• Dual plumbing: separate pipes for fresh water and treated water.
• Collection factor: the share of rain on a roof that can actually be captured, always less than one.

With these few words and the arithmetic above, you can read any water claim with a calm, clear head.

The bottom line

A water claim is only as good as the plan behind it. Look for a named source, real storage, treatment and reuse, recharge you can see on the site plan, and meters for each home. Ask for the features in writing, check them on your visit, and treat any percentage as a starting point for questions. That way, the water plan you buy into is the one you will actually live with.

Water is a top worry for buyers on the Sarjapur–Attibele Road. Ask us about our project's water plan; we will show you features, not slogans.