Rain Water Harvesting Project
When it came to self-sustainability, I was interested in doing three projects -- growing organic vegetables, setting up water harvesting and generating power from solar panels. While we cannot certainly be fully self sustaining if I completed the projects, we could at least be less dependent on outside factors. A while ago we started growing vegetables in our side yard and terrace. I need to get around to writing a post on it. Some topic or the other always comes up and I write a post on it and eventually the post on terrace garden is way overdue. I did not want to let the same thing happen to this project which we started working on setting up recently. So here is something on that topic. The work is not yet fully done, but if I wait, I may end up never getting around to it :)
Inception of rain water harvesting
It was the start of monsoon season, we were thinking of harvesting rain water, because we could see the acute pressure on water resources during the most recently concluded summer months. We already have rain water harvesting pipes collecting terrace rain into a covered harvesting pit to charge groundwater. But we did not have a borewell, so all the water is just going unused. I wanted to change that and build something myself that would collect the rainwater for our use. You see, with so much free time at hand, you tend to get these silly ideas. Anyway, we have a couple of pipes running from the terrace to the ground like shown below --
Collecting the rain water
The plan was to cut out a small piece from one of the pipes and divert the water away from the ground. The diverted water should go through a filter and into a drum to collect the water. So here is the story in pictures --
If everything works according to plan, the terrace rain water thus collected by the pipes should arrive in the drum instead of underground. Fortunately for us, we had a shower the very next day so we could test our setup and everything worked out well. There were no leaks, but as expected the pipe was swaying a bit due to wind and rain water flowing through it.
The next step is to attach a final pipe that will reduce the water drop from a height of 6 feet to closer to the height of the drum. Then clamp that pipe to the wall so the diversion pipes stay put even on a windy day.
Diverting rain water to sump
Now that the pipe is secured, the water can get collected in the drum below it without spilling the water everywhere. Next we have to make arrangements for the water in the drum to flow out and into our water sump from whence the water will be pumped to the overhead tank. For that, the plan was to make a hole close to the bottom of the drum and fix a tap. The story continues...
Done with the tap, and now we need to filter the water so as to avoid all the dust and leaves from entering the system. We took an old thick cloth, folded four times over and used it as the filter. The filter will be at the opening of the drum and as water comes out of the spout it gets filtered and can be collected from the bottom tap. The next plan is to connect a pipe at the bottom tap which will divert the water to the sump. So those steps in pictures
The setup is essentially complete, now for some testing and fixing any bugs ;) . We dumped a bucket of water to check the flow rate, and leaks in the system.
Changes to filtering
With that, we come to the end of the rain water harvesting project. We have come a long way indeed, but still a lot more work to do. This was our initial setup, and after each rainy day we kept on making more improvements. For example, we found that the thick cloth was getting clogged pretty quickly after just a few minutes of rain and then the water was not passing through it anymore.
So we decided to use two levels of filtration. The first filter is a more porous cloth, and the next filter is a cloth with a bit less permeability. Then we added another filter to the end of the pipe that leads to the sump so as to limit any frogs or insects entering the pipe. We also closed the mouth of the sump with a semi transparent cloth to avoid leaves and dust from going into the sump when we leave the door partially open to let the water harvesting pipe in.
Most recently we noticed that the single 1 inch pipe is unable to drain out the water from the drum fast enough during heavy rainfall. So the drum is filling up and overflowing even as the 1" pipe is draining water from the drum. So my plan is to add an extra drum and also to connect two more taps so the flow rate will be three times. Lets see about that. Update: We fixed the issue. Read all about it in the update post.
We are still collecting only half the rain water. Remember I said we have two rain water pipes connecting from the terrace to ground? We've setup collection only at one pipe. In future we need to work on setting up something similar for the other one. I am surprised by the amount of water we have been collecting since the setup. Pretty happy with it. More work to do though.