Hi Guys
I've moved into a new home (about 4 years old) brick and tile…there are 2 rain water tanks outside with a pump attached to it (that water is used inside house for toilets, laundry, and outside garden hose).
There is a problem with it that since there are 2 rain water tanks, there is only one tank that is always re-filled by mains tap and used and the other tank just stays full and no water is used from it. (Both the tanks are connected via a pipe in the middle)
Thank you for your help.
Pretty sure its not blocked, I will post some pictures of the setup in a few hours that I have just coz its sort of hard to explain
We have a similar system to your set-up, however in ours, the 2 tanks are connected via a pipe between them, so that the water fills into one tank, which flows across to the other one which is where the water pumps out from… so they both fill at the same rate / height. You might want to check that they aren't connected some how, as it would seem very unusual to have one unused.
Sounds weird to me that a rainwater tank would be constantly refilled from the mains tap!
If the toilet and laundry are fed solely by the rainwater tank and not plumbed to the mains system, then the system is probably designed for the mains supply to fill the tank if it gets too low to ensure continuation of supply… eg in times of drought.
It sounds to me like the pipe linking the 2 tanks is blocked. The one that is 'always full' of rainwater should be flowing into the other tank, where the pump feeds from. However, because the rainwater is not flowing through, it is just always being 'topped up' by the mains supply to keep the water flowing in the house.
In any case, call a plumber and have it checked out!
I get the concept of using the water from these systems but I admit I have never seen one up close or know how they are plumbed. If they have to top-up from the mains, I would assume that would not happen until the level was low, and only then top up say 50-100 litres, enough for a laundry load and a few toilet flushes. This way there would be sufficient empty space to catch more rain water or certain waste water (this is called greywater and should have purple coloured fittings and pipe). This would be the whole idea of having a tank in the first place; if you were constantly filling from the mains you might as well have a direct connection anyway and eliminate the expense and complexity of having tanks.
If there is a pipe between them, I assume it is low to the ground? This would ensure the level in one tank would be exactly the same in the other one. The only reason for having it would be to double the capacity of the tank. That would suggest a rainwater-only system to me. If it were up high, I would imagine one tank is for collected greywater and the other is for rainwater. When the rainwater tank is full it overflows into the collected greywater tank, which itself has an overflow into the sewer, but at a slightly lower level than the crossover. This way the rainwater tank stays clean and can only flow one way into the "dirty" water. Do the tanks have taps on them? Is one tap purple and the other one normal? If so it could be that there is a rainwater tank available for you to use on the garden, as well as having a greywater tank for flushing. If you never use the rainwater on the garden, that tank is going to remain full.
I'm not sure if you would use greywater for washing your clothes though, considering it is collected from places like the shower, it would be dilutely contaminated with shampoo, dirt, sweat, soap and potentially fecal matter and other bodily fluids. That's why it's clearly plumbed with purple pipes so you don't drink it, but it is clean enough to flush the toilet.
In our local council area, there are special regulations required to install a tank that is greater than 10,000L , so we have 2 x 10,000L tanks, joined by a pipe, effectively giving 20,000L storage without the need for the additional council regulations to be applied for.
It is becoming more common for rainwater tanks to be plumbed into the house for use in laundry/toilets. Many councils now require any major renovations or new houses built to incorporate rainwater tanks. The OP states his house is only 4 years old, so this would make sense.
If they are both connected, and there is no blockage, in theory it's not possible for one to remain full all of the time, so would love to see your pics to get a better understanding.
Well I can't understand why rainwater tanks are filled with mains water??
It would be logical if …let's say the "feed tank"… is filled with "grey water" from shower, clothes washing etc.
But, if you want to disable the mains feed…it must be filled using a ball cock (like a toilet tank). If you can access the tank…tie off this mechanism, so that it doesn't operate when the level goes down. I presume that through a gravity feed the other tank's contents will then flow into the "feed tank". Problem is, both tanks will remain half full! (unless the rainwater tank is much higher than the feed tank …which would make sense!)
Because if there is no rain, and the rainwater tank is empty, how will he flush the toilet in the house? There needs to be a back-up source of water for times of low rainfall. It makes much more sense to simply put a mains water connection into the tank that only turns on when the water level gets low, vs plumping the entire house with 2 sets of pipes, one from the mains and one from the tanks.
What you say may be correct, but I was addressing the question that I believe the OP posed…how to use the water in the rainwater tank rather than continuously use mains water?.
A mate of mine has a (somewhat) similar system, where he has a tank filled with "grey water" which he uses to flush toilets and water lawns etc and which he can manually top up from a second "rainwater tank" or from mains, although I don't believe he uses any of the stored water to wash clothes, but I may be wrong.
Is there a antibackflow device inbetween the tanks? could be installed backwards
This is a reply to an old thread because a suitable answer does not seem to have been given and the following may help someone else problem solve.
The balance line between the two tanks will not be blocked if water has passed through a mosquito proof screen as per the regulatory requirement but either one or both of the two outlet valves could be closed or else a spindle has broken on a gate valve, leaving the valve shut but allowing the tap to turn…which can happen.
The only other possibility is if there is a check valve installed backwards in the balance line as suggested by the previous poster but this scenario, while possible is not probable. When there are two tanks, water should be diverted to one tank and decanted water from that tank should then flow to the second tank that only supplies water to the pump.
oops, wrong thread.
Have you tried pushing a wire through the pipe to see that its not blocked up?