After I made the switch from soap, I started observing our water consumption at our household. We were consuming about 1000 litres of water everyday. The first thing I observed was that we waste a lot of RO rejected water. Like I mentioned earlier, the water we receive from the municipality as well as private tankers are sourced from borewells that go as deep as 1600ft below ground-level. The water hardness level in my locality is around 800ppm based on a recent test we did at our house.

Our Reverse Osmosis (RO) based water purifier rejects about 6-8 times as much water for every cup of pure water we draw out of it. That means, if we use about 20 litres of water everyday for cooking and drinking purposes, the machine rejects close to 150 litres of water!

Having been eco-sensitive always, my Dad had let out the reject water to the plants in our backyard. When I measured that amount of water rejected, I realised we were sending more water to the plants than what they needed. This made me rethink our water handling habits.

  1. We had to use the RO reject water in a better way. Using it to water about half the plants we have is not a solution.
  2. We had to reduce the consumption of water for washing utensils and clothes.
  3. We generally water the plants using a mug and bucket approach. That means, we are still providing the plants more water than they need. We had to reduce the amount of water we use to water plants, given that every drop of that serves the purpose of drinking for us.

Between April 2017 and now, I’ve taken quite a few steps towards achieving the above objectives and I’ve seen measurable results. In this post, I’ll be sharing what we did to achieve objectives 1 and 2. The solution for objective 3 will be shared in a future post.

Dealing with RO reject water in a better way

The RO reject water in my kitchen is sent to the narrow backyard using an outlet pipe that goes through our kitchen wall. We had to drill a 1/4 inch hole into the kitchen wall to push the thin pipe through it. Before this, we were letting all the reject water into the sink and I’m sure most people do the same in Indian cities.


RO Reject Outlet through the Kitchen Wall

We had placed an old drum outside that used to collect the reject water and my Dad used to water the plants with the collected water. Now, when my Dad constructed this house in 2003-04, he had built a small underground storage for water next to the kitchen. He had also placed a 200 litre tank on the terrace at the first floor. His idea was that he’d collect drinking water in the tiny underground sump and then pump it to the tank on the first floor. For various reasons, his project had failed.

I made use of this existing infrastructure to improve our water collection and storage system. First, I had the 1000L tank on the second floor and the 200L tank on the first floor connected to each other. A ball-valve system in the 200L tank ensures that the tank stays full by drawing water from the bigger tank above. This helped us increase our above-the-ground storage to 1200L. Since the smaller tank was already connected to a single tap in the kitchen, we shifted our RO plant to use this connection. This step ensured that we have a separate drinking water storage and can survive for a few days more if we run out of water in the main storage.

Next, I cleaned up the small sump and let the RO reject outlet pipe into this sump. This allowed us to collect about 110-120 litres of rejected water in an additional storage that is separated out from our regular storage. Now, we had to figure out how best to use this collected water as against watering the plants.

We observed that our maid is one of the biggest consumers of water in our household. We saw that she has the habit of keep the tap running for about 15-20 minutes as she goes about washing the utensils. And, washing utensils didn’t have to use the water that we could make potable!

We placed a drum in the area where she washes the utensils. I bought a 14W aquarium submersible pump from a pet store and placed it in the 110L underground sump. Some basic civil works like drilling a hole manually with a chisel and hammer was involved in order to pull the outlet pipe as well as the electric connection wire from inside the sump to the ground. The outlet pipe of the pump fills up the drum in the backyard which the maid now uses to wash the utensils.


Water from sump is pumped into this drum

We also decided that we’ll wash clothes in the washing machine weekly in two to three lots as against the existing practice of washing them daily.

These two simple steps costing about INR 1000/- ensured that the 11000L of water that we collect in our main underground storage sump can now serve us for about 22-25 days as against 8-10 days before we adopted these changes.