Harvested rainwater for non potable use in the home

[osolemio]

Originally Posted by Piwoslaw

Good for you!!


Is there some kind of filter system between the roof and the underground tank? If not, is the cistern easy to clean periodically? What kind of roof do you have? Our roof has shingles and I keep cleaning the sand out of our barrels. Plus lots of pollen in the spring, and dust after a few dry days.


Maybe a heating element in the rain gutters? I'm not a fan of wasting electricity, but that may be worth the extra water.

This tank installation requires that there is no hindrance from gutter to tank. Normally one would put a "sand catching" vertical tube, where the sand and other heavy particles would fall to the bottom. I think in this case, they don't want the idling water to sit there and catch bacteria? Or maybe the flow or ...

In any case, I have thought of some kind of filter in the gutter - I just need to make sure I remember to clean it now and then.

As for the tank - pollen floats to the top, sand goes to the bottom, so as long as the water is taken from just below the surface, I should not need to clean the tank that often.

I think the electric gutters will be too expensive. With falls usually being quite wet, I would imagine I would have close to a full 7500 liters / 2000 USG approaching december, so the period of no water should be short - if any. In normal winters here, there are usually periods with thawing - only recently was a bit odd, with several consecutive months of no positive temperatures at all.

[Piwoslaw]

One more question: what happens when the cistern is full? Where does the overflowing rainwater go? Sewage, or underground?

Sorry about the dumb questions, but I'd like to store some rainwater underground and would like to know which technical problems I'll need to solve along the way.

[osolemio]

Originally Posted by Piwoslaw

One more question: what happens when the cistern is full? Where does the overflowing rainwater go? Sewage, or underground?

Sorry about the dumb questions, but I'd like to store some rainwater underground and would like to know which technical problems I'll need to solve along the way.

The cistern is the small container inside the pump/control unit, which mixes mains water into the rain water pipes in case the rain water tank is empty. The cistern is used to ensure that there is no physical possibility for rain water to be pumped back into the mains water.

The rain water tank is prepared for overflow. This can either go to the sewer, or you can install an infiltration cavity in the ground. Depending on how well the soil absorbs water (this can easily be tested), you need a certain size to ensure you can process all the excess water.

I am using the infiltration cavity solution. It is a mesh of environmentally friendly plastic units, combined to a larger box which is then encapsulated in a fibertex membrane (to keep dirt out). I have specifically made mine so that I - besides the sand catching unit - have a vertical 110mm tube extending from the infiltration unit bottom, to the surface.

This enables me to see the level of water inside, and if it tends to build up, I will consider installing a farm-type mechanical pump, for irrigation purposes. The water in the infiltration box is sufficiently clean to use for this purpose.

By disconnecting rain water entirely from the sewer, I get a cash refund, which is quite substantial (about 3000 USD), as it helps save the sewers from overflowing when it rains a lot in a shorter time. If enough people did this, we would not have those expensive overflows, flooding peoples basements and overflowing the sewage cleaning plants thus polluting lakes and streams.

[munter]

I now have a mixed source supply for our toilet cisterns. The schematic is much like a manual version of the schematic posted by Tango Charlie. Instead of solenoids, I simply use ball valves. Our plumbing code requires double check valves to ensure no backflow as well as a check valve to make sure the mains water doesn't go back up through the pump and into the tank. The outlets are connected to the toilet cistern and the clothes washing machine. I have noticed very few drawbacks to using rainwater as a source. We are getting through about 100L/day of rainwater, most of which is inside the house.

[osolemio]

Originally Posted by munter

I now have a mixed source supply for our toilet cisterns. The schematic is much like a manual version of the schematic posted by Tango Charlie. Instead of solenoids, I simply use ball valves. Our plumbing code requires double check valves to ensure no backflow as well as a check valve to make sure the mains water doesn't go back up through the pump and into the tank. The outlets are connected to the toilet cistern and the clothes washing machine. I have noticed very few drawbacks to using rainwater as a source. We are getting through about 100L/day of rainwater, most of which is inside the house.

We cannot do that, no matter how many check valves. It MUST be a cistern solution, water entered into a tank, before a pump. After the rainwater pump, no pipes may connect physically, whether check valves, or any other control ..

I am working on an idea of cleaning the water further, using a fine filter as well as UV light in the rain water tank.

One solution could be a "cistern" at the top of the shower. Then hot mains water can enter this cistern together with cold rain water, in a way where it cannot mix (partly open cistern). This "cistern" would have an opening underneath, so the water would free flow through many smaller holes.

Mixing the hot mains water (solar heated) with the rainwater would provide much less limestone (if any), and you can still regulate the temperature by changing the flow of the hot mains / cold rain water ...

Taking it even further, if I could find a way to make instant heating of the rainwater using stored solar heat, but it must be in a way where it does not get too complicated. And it should run automatically.

I would not even be concerned using rainwater as it is, for showering (no filtering at all), except for the steam from the water could carry possible ecoli bacteria into the lungs. Hence the UV light and fine filter.

[Piwoslaw]

Osolemio, could you just heat rainwater for showering through a heat exchanger? The hot mains water wouldn't mix, only give off some of its heat.

[osolemio]

Originally Posted by Piwoslaw

Osolemio, could you just heat rainwater for showering through a heat exchanger? The hot mains water wouldn't mix, only give off some of its heat.

Yes, that is one solution. But if you want to keep the comfort of being able to adjust the temperature, not just a fixed one, you would still need to have hot and cold separately.

For me it is no issue, though, as I have so many heat buffers in my system so I could really have a heat exchanger for this purpose. The question is whether or not it is getting too complicated and expensive, to have a parallel heating system, for rainwater ...

[fishaholic]

Originally Posted by wyatt

I proved two things, and disproved one!

Experiment:
Attach a siphon hose to the tank inlet, see if gravity feed will fill the tank.
Hypothesis:
Yes, it will.
Method:
No siphon hose available... no hose available... made a hose out of plastic, duct taping the seam, duct tape the "hose" to an old tank fitting. Fill "hose" with water until the tank starts to fill.
Outcome:
Tank didn't fill, even when water was one foot over the rim.
Dis-proved hypothesis!
Proved that "hose" didn't hold water well (leaked like crazy)
Proved that the tank required pressure to activate. How much pressure is unclear.

I was hoping I could get video of it working... no such luck. The tank actuator (at least mine) is pressure activated. A better experiment with better quality components would be needed to determine if a gravity feed system would be able to fill a toilet tank. Sorry, I guess I have to leave that one up to you.

try setting a barrel on the roof and see if the drop adds enough pressure to accuate the fill tube.