Short answer
Is rainwater harvesting compulsory for a house in India? Not everywhere. The national model bye-law says buildings on plots of 100 square metres and above 'shall mandatorily include' a rainwater harvesting proposal when plans are sent for sanction (clause 9.1), but a model binds nobody until a state or city adopts it. Whether it is compulsory for your house depends on your city's bye-law, which your local body can confirm. The two methods are storage for reuse and recharge of the ground.
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Rain that falls on a roof can run off into a drain, or it can be kept. Rooftop rainwater harvesting keeps it, either in a tank for later use or in the ground through a recharge structure. Many owners hear that it is “compulsory,” and some cities do require it. This page explains the two methods, the parts of a simple system, where the rules apply, and what an owner should check. It gives no tank or pit size, no cost, no penalty amount and no rainfall figure. Those depend on your roof, your soil, your city and an engineer’s design.
What are the two methods?
The model bye-law describes two main techniques: storage of rainwater above ground for future use, and recharge of rainwater into the ground (clause 9.2). The table sets them side by side.
| Method | What it does | When it is used |
|---|---|---|
| Storage | Collects rain in a tank or sump and keeps it for cleaning, watering the garden and similar use | When the house needs water and the tank can be kept clean and covered |
| Recharge | Sends rain into the ground through a pit, trench or well, to add to the groundwater | When the soil and the groundwater allow water to soak in; the model text lists pits, trenches, tube wells and combinations |
| Combined | Uses both: a tank for use, with a recharge point for the overflow | Where the bye-law asks for both, or the owner wants both |
Table 9.1 of the model says that, for residential plots of 100 square metres and above, the storage provision “shall have emphasis on both storage and reuse.” Clause 9.5 says recharge should be made mandatory for buildings in its own clause. The two are separate requirements.
What parts make up a simple system?
The model bye-law lists the main components (clause 9.1: roof catchment, gutters, downpipes, drains, a filter chamber, storage tanks, pits or sumps, and recharge structures). A simple house system also needs the parts below, which the model does not list:
- Catchment. The roof that collects the rain.
- Gutters and downpipes. To carry the water from the roof to the storage or recharge point.
- Leaf screen and first-flush. To keep leaves and dirt out, and to let the first rain, which washes the roof, run away. This is practice; the model bye-law does not list these parts.
- Filter chamber. To clear the finer dirt before storage or recharge.
- Storage tank, sump or recharge structure. Where the water goes.
- Overflow. To take the extra water away from the house.
When is it compulsory?
The national model bye-law says that buildings on plots of 100 square metres or more “shall mandatorily include” a complete rainwater harvesting proposal when the plans are sent for sanction (clause 9.1). But that is a model. It binds no one until a state or city adopts it into its own bye-law. The model text itself is not consistent: a different sub-clause sets a separate rainwater provision for recharge on residential plots over 2000 square metres (clause 2.10.7(b)(ii)). So the rule that governs your house is the one in your local bye-law, and your local body can confirm it.
Some places have acted:
- Delhi. The Unified Building Bye-Laws 2016 (compendium amended in February 2020) apply the green-building provisions to plots above 105 square metres (clause 10.1). Their sanction provisions (clause 10.2, Table 10.1) include rainwater harvesting by recharge for plots above 105 square metres. Check the current text with the local body before relying on it.
- Tamil Nadu. In 2003 the state amended its municipal building rules so that every owner or occupier of a building under them had to provide a rainwater structure by 31 August 2003. A building without one by 10 October 2003 could have its water supply disconnected (rule 3-B). Those 2003 deadlines have passed. The current rule was not checked for this page.
- Bengaluru. Reports say the Bangalore water and sewerage law was amended in 2021 to require rainwater structures for larger sites. The thresholds vary from report to report. No primary source was found for this page, and the amended law was not read. Check with the water board.
Other cities have their own rules, and some of them have changed. Do not rely on an old list. Ask the local body whether rainwater harvesting is required for your plot, and whether it is checked before the completion certificate or the water connection.
What should I check before I build?
- The local bye-law for your plot and whether it requires storage, recharge, or both.
- Whether the groundwater and soil suit a recharge structure. The state groundwater department and the site engineer can tell you. Water that cannot soak away is a problem for a pit, not a solution.
- The distance of any recharge structure from the house foundations. Ask your engineer and the local body to set it.
- Whether the storage tank will be above or below ground, and how it will be kept covered.
- Where the overflow goes. It should run to a drain, away from the walls and the plinth.
- Who will clean the screens and filters, and when.
What mistakes should I avoid?
These are practice points, not standard rules.
- Treating a recharge pit as a soak pit. A rooftop recharge structure is not the same as a sewage soak pit. Sewage must not go into a rainwater pit. See the soak pit page for the difference.
- Joining the roof drain to the sewage system. Rainwater should be kept separate from the toilet and sink drains.
- Leaving the tank open. An open tank or an open overflow can breed mosquitoes. Cover the lid and cover the overflow and air vent with mesh.
- Assuming the water is safe to drink. Roof water can be contaminated on the roof, in the pipes and in the tank. Treat and test it before drinking; this page does not give a household treatment method.
- Skipping the maintenance. Clean the gutters, the screen and the filter before and after the monsoon, and check the tank for cracks and leaks.
- Building before checking the soil. A recharge pit in soil that does not drain will fill and stay full.
What should I check after the first monsoon?
- The tank for cracks or leaks. See the water tank leakage page.
- Water staining at the base of the walls, or near the foundation.
- The overflow, to check it runs away from the house.
- The recharge pit, for standing water or silt.
- Mosquitoes or their larvae in the tank, the overflow or the gutters.
- The roof outlets and gutters, for blockage. The pre-monsoon checklist covers them.
Frequently asked questions
Is rainwater harvesting compulsory for every house in India?
No. The national model bye-law makes a rainwater proposal mandatory in its text for plots of 100 square metres and above, but it binds a house only where a city or state has adopted it. Check your local bye-law.
What is the difference between a recharge pit and a storage tank?
A storage tank keeps the rain for your use. A recharge pit sends it into the ground. Some systems do both.
Can harvested rainwater be drunk?
Not without treatment and testing. Roof water can carry dirt and germs from the roof, the pipes and the tank. Ask a water-quality expert before you drink it.
How do I know if my soil is suitable for a recharge pit?
Ask the site engineer or the state groundwater department. Water that does not soak away will stay in the pit.
Related guides
- Water tank size for a house
- Soak pit vs septic tank
- Pre-monsoon checklist for house and site
- Recharge pit for a borewell: how it works and when not to do it
This guide is general information. Read the disclaimer. Your local body, your engineer and the state groundwater department decide the rainwater system for your house.
Sources
- MoHUA (earlier TCPO), Model Building Bye-Laws 2016, Chapter 9 (rainwater harvesting), clauses 9.1, 9.2, 9.5 and 9.6, and Table 9.1 (a model for states and local bodies to adopt). Clause 2.10.7(b)(ii) read for the threshold conflict.
- Delhi Unified Building Bye-Laws 2016, compendium amended to February 2020, Chapter 10 (green-building provisions), clause 10.1 and Table 10.1.
- Government of Tamil Nadu, G.O. Ms. No. 56 (21 July 2003), publishing amendments to municipal building rules including rule 3-B. Historic text; the current rule was not checked.
- BIS listing for IS 15797:2008, Roof Top Rainwater Harvesting: Guidelines (listed as current; the text was not read for this page).
Change log
- : Added Related guides link to newly published article(s): recharge-pit-for-a-borewell-how-rooftop-rainwater-recharge-works-and-when-not-to-do-it. No other text changed. Approved by the reviewing engineer.
General information only. It is not a structural design or professional advice. Ask a licensed structural engineer or architect to check your plans and site.