This Simple At-Home Rainwater Harvesting Guide Can Help You Save Thousands of Litres

Every year, the monsoon brings chaos to Indian cities — flooded streets in Mumbai, overflowing drains in Delhi, waterlogged homes in Kerala. But amidst this mess, there’s something most of us forget: all that water rushing away is a resource we could use.

Why harvest rainwater? 

India receives about 4,000 billion cubic metres of rainfall annually, yet most of it goes to waste. While urban centres battle waterlogging, they often face severe water shortages just months later. The irony? All that rain could have been stored, filtered, and used to recharge borewells, reduce bills, and keep households running through dry spells.

Rainwater harvesting is a simple, low-cost solution that addresses all of this. By capturing and storing rain, you can:

• Reduce your dependency on tankers or municipal supply
• Recharge your borewell or open well
• Cut down your water bills
• Contribute to groundwater conservation
• Avoid waterlogging around your home during monsoon

As Dayanand Krishnan, a Chennai-based engineer who’s been harvesting rainwater since 2002, using a simple method, puts it, “The entire system required only Rs 150, and can be installed by anyone at home.”

Here’s how you can get started, in just 5 simple steps.

Step 1: Assess your catchment area (usually your roof)

The rooftop is the most common and cleanest place to collect rainwater. Check how much flat surface area you have. People working towards rainwater harvesting have identified that if 25mm of rainfall is received, around 2,000 litres can be collected from a rooftop spanning 1,000 square feet.

Make sure the roof is clean and free of dust or animal droppings. Install mesh filters at outlets to stop leaves or debris from getting into your pipes.

Step 2: Install a rainwater collection system

Rain falling on your roof travels through downpipes (drainage pipes). You will need to connect these to your harvesting system. You can either store the water in a tank or let it percolate into the ground.

The basic components of a collection system include:

• Gutters to channel rainwater from the roof
• Downpipes to carry the water
• First flush diverter, which discards the first rain (which may contain dust)
• A filter chamber to clean the water before storage or recharge

Dayanand’s rainwater harvesting method relies primarily on these exit pipes, and he can collect 225 litres of water with just 10 minutes of rain. “Every terrace, and most balconies, have an exit pipe attached, which directs the water out. My trick was only to secure the ends of these pipes and get them to collect water in the drums. I also put a cloth filter at the endpoint,” he adds.

Step 3: Choose your harvesting method – storage or recharge

Option A: Storage for Household Use

Collect filtered rainwater in tanks or barrels. You can use this water for:

• Gardening
• Flushing
• Cleaning
• Even drinking and cooking, if filtered and treated well

Use HDPE (High-Density Polyethylene) or cement tanks, place them on a platform, and keep them covered. Overflow pipes must be added to prevent spillage. 

Option B: Recharge your borewell or well

If storage isn’t your priority, help nature instead. Channel the clean rainwater to a recharge pit near your borewell or open well.

A typical recharge pit is three to four feet wide and six to eight feet deep, filled with gravel, charcoal, and coarse sand to act as a natural filter. This lets water slowly seep underground. Many households, like those featured in The Better Home, have revived dried-up borewells using this simple technique.

Step 4: Filter it right

Filtration is crucial. Even if you’re not drinking the water, unfiltered rainwater can clog pipes or contaminate recharge pits.

A good DIY filter includes:

• Pebbles (bottom layer)
• Coarse sand (middle layer)
• Activated charcoal (top layer)

You can build your filter barrel or buy ready-made filters (starting at Rs 1,500 to Rs 5,000). Regular cleaning is essential to keep it working.

Step 5: Maintain and monitor

Once your system is in place, maintain it regularly:

• Clean your roof before every monsoon
• Flush the first rainwater away
• Clear out filters and pipes after every major downpour
• Check for leaks, blockages, or algae growth in your tanks

Also, track how much water you’re collecting. It helps you understand your impact, the reduction in water bills, and even tweak the system if needed.

Bonus tips

No rooftop? Try terrace canopies, small courtyard systems, or even balcony collection for plants.

Don’t have a borewell? Recharge a nearby community well or create a soak pit in your yard.

Live in an apartment? Convince your Resident Welfare Association (RWA). Shared systems can benefit all residents.

Setting up a rainwater harvesting system doesn’t require deep pockets or engineering degrees. It requires intent, basic tools, awareness, and a love for the environment. People like Dayanand Krishnan and hundreds of others have shown that with a little effort, we can turn every home into a water-positive space.

This monsoon, let every drop count: harvest rain, recharge the Earth, and revive your water sources. And all of this can begin with your roof!

Edited by Vidya Gowri Venkatesh.