Rain Water Tank

Collect and Use Rain Water (Rain Harvesting)

I like projects, An if i can incorporate a little saving and possible environmental kindness then why not. I do not live and sleep like an eco warrior but it is easier to implement things while its still in a mess rather than retrofit. 

It also helps if you have a target to hit, mine was my final year project study for a HND. Design an eco water bottle, a new type of loo seat, come on. How about a PLC that can pump water from a tank to fill the toilets with re-claimed rain water! 

The Project!

The plan is to collect rain water from all the house down pipes and run it into a central ground storage tank, this will need a filter to stop any of the sand or other items entering the tank, The water will be pumped into a loft header tank once per day (not on demand), water is then gravity fed to the toilets by separate pipework at the water is classed as non-potable (non drinkable)

Sounds like its expensive ?. Now i do all the work myself and its my design so what will i need.

Central collection for down pipes, Filter, PLC controller, Water pump, Ground pipe, Loft tank, Ground tank and some switches. 

Now before you go running out to get these bits, there was a little planning here, When I built the extension I always try to look ahead, So I added separate pipe work for all the toilets just in case, At the time I had a new boiler that did not need the header tank, so that was saved and kept in the loft, Just in case I ever got around to this project.

I need a PLC, Arduino, Raspberry Pie, or even an old Eaton easy Pc (which i already had from ebay)

Water Pump, A trip to Machine mart got me a 40Head Pump tor 280.00

Filter, Simple Paper cartridge type (big one to not affect flow rate)

Central collection, part of my ground works its called a Wiz Filter (see later)  

Pipes, Wickes and B&Q for that 

Plastic ground tank, Hmm this could cost £500.00+ and must be concreted in. So is there another way! 

Try This. I have seen man holes with ladders in them and at the bottom is some kind of water flow. They don't fill-up and are generally dry. So if I were to plug the hole the reverse would work right ?

So here we go and it worked a treat.

Techi bit. I also wrote the control software for the PLC which controls the pump times and water storage times. But that's another story !

Update (202)

This thing is still going strong, Not one issue so far :

Well i did say do it while there is a mess!

This was "I know an man" moment, if you can find a small subcontractor (smaller the better) their overheads will be lower and costs will fit a smaller budget. I also need to remove the excavated mud so another man and van.

I wanted a 2m x 2m x 3m deep hole, and that's what i got. The next day was an eye opener and doing this again would have prompted an additional step. The water table here is quite high and I came back to a meter of water at the bottom. I had to pump out the water and dig a little in one corner, fill with pee gravel and install a small sacrificial tube to allow a small pump to keep out the water while the concrete sets.

The first pour of concrete is to create a base for the upper rings to sit on. An order of 1.5m cubed was ordered to give me an aprox 400mm deep base. We also lowered in the top ring and allowed it to sink in about 50mm to help with the base seal. 

Once the concrete had solidified the second ring was added with a cement seal allowed to set ready for the second pour is to seal the sides of the tank and prevent it from moving around.

I dropped in a little left over steel re-enforcement, Yes I know it should have been submerged, but not until i had done it. Remember this was a learn as you go project.

To get the pipes in i used a diamond pipe cutter in my drill, it took a while but made the pipes easy to seal. The inlet was placed about 20mm  lower than the inlet

Preparing the tank for its concrete lid

And here it comes, not something you can lift by hand.

This was a bit tricky, my man hole cover needs to be just at the right height to be level with the blockwork when its in place. Getting this right will make the tank almost invisible, wrong and it will look positively duff. And notice the ring has to fit in a square hole, now that was not in the plan.

This is the wiz water filter that brings all the rain water into the tank, i have to dig a hole about 2 meters down to get this in, and the mud is hard as rock, 

Water filter, this was the biggest i could get my hands on, contains a paper element. The sellers advices was it probably would never need cleaning, but i will be cheeking in 6 months. I have also placed a stop valve on the out flow, this is to stop the water in the pipe draining backwards when removing the filter (no puddles thankyou)

Nice multi stage pump with about 40 head, it also has a large one way valve so the pump does not have to re- fill the pipe each time it runs. The float switch keeps the pump from running dry, in this situation the loft tank level drops and will be detected by the PLC to bring on the clean water supply to top up the loft tank.