Hello,
After searching online for a long time, I believe I have not yet looked for the right solution.
We are currently building a new house and plan to use a rainwater cistern to water the garden later. However, there are a few conditions to consider.
1. Excess rainwater must not flow into the sewage system.
2. Excess rainwater must be discharged into the street.
3. The cistern will be located below street level.
This means we need a system to pump the overflowing water up to the higher street level.
I have already looked at various pumping systems. However, from an ecological perspective, the cistern does not make much sense if the benefit is offset by using a pump. Also, so far, I have mostly seen submersible pumps, which would not remove debris from the surface water of the cistern.
Hoping that we are not the first to want to use a cistern under these conditions, I look forward to any valuable new suggestions.
Best regards,
FlorianBaaske
After searching online for a long time, I believe I have not yet looked for the right solution.
We are currently building a new house and plan to use a rainwater cistern to water the garden later. However, there are a few conditions to consider.
1. Excess rainwater must not flow into the sewage system.
2. Excess rainwater must be discharged into the street.
3. The cistern will be located below street level.
This means we need a system to pump the overflowing water up to the higher street level.
I have already looked at various pumping systems. However, from an ecological perspective, the cistern does not make much sense if the benefit is offset by using a pump. Also, so far, I have mostly seen submersible pumps, which would not remove debris from the surface water of the cistern.
Hoping that we are not the first to want to use a cistern under these conditions, I look forward to any valuable new suggestions.
Best regards,
FlorianBaaske
F
FlorianBaaske3 Aug 2019 19:01Thanks for the responses.
Maybe a few more details.
According to city regulations, drainage into the sewage system is not allowed; instead, it must be drained onto the street. The surface water is then directed into soakaways. Infiltration on the property itself is not permitted. We initially considered a deep infiltration trench, but the soil conditions do not allow it. So the only option left is overflow onto the street.
With some luck, it might be possible for the overflow from the cistern to be located below the house’s slab foundation but still above street level. However, this would cause backflow into the roof rainwater drainage pipes, as these pipes are already installed up to 80cm (31 inches) deep. This cannot be changed anymore since the pipes are beneath the completed slab. I do not think this is a good solution, even though the city considers it practical.
The pump would not have to overcome significant height differences (just a few centimeters). However, the pump should not start immediately during light rain, run for 2 seconds, then stop again because there is too little water coming from the roof.
The cistern itself has a capacity of 3000 liters (about 790 gallons). Are there pump systems that start pumping at a certain level X and continue pumping down to a lower level x-y, so that the pump does not keep switching on and off during light rain?
A system that serves both for irrigation and as an overflow system would, of course, be the best solution. So far, I have not been able to find such a system.
Maybe a few more details.
According to city regulations, drainage into the sewage system is not allowed; instead, it must be drained onto the street. The surface water is then directed into soakaways. Infiltration on the property itself is not permitted. We initially considered a deep infiltration trench, but the soil conditions do not allow it. So the only option left is overflow onto the street.
With some luck, it might be possible for the overflow from the cistern to be located below the house’s slab foundation but still above street level. However, this would cause backflow into the roof rainwater drainage pipes, as these pipes are already installed up to 80cm (31 inches) deep. This cannot be changed anymore since the pipes are beneath the completed slab. I do not think this is a good solution, even though the city considers it practical.
The pump would not have to overcome significant height differences (just a few centimeters). However, the pump should not start immediately during light rain, run for 2 seconds, then stop again because there is too little water coming from the roof.
The cistern itself has a capacity of 3000 liters (about 790 gallons). Are there pump systems that start pumping at a certain level X and continue pumping down to a lower level x-y, so that the pump does not keep switching on and off during light rain?
A system that serves both for irrigation and as an overflow system would, of course, be the best solution. So far, I have not been able to find such a system.
A solution with a pump and sensor is not really complicated. I’m not sure if a ready-made version is available, but probably yes. For example, pump control with two sensors.
It can also work with float switches...
I wouldn’t use a rain sensor for this, but rather a level sensor. Otherwise, you’ll lose water. With 3000 liters (790 gallons) there isn’t that much anyway.
If you already have backflow issues, it might also be an option to use a backflow preventer. However, the system would need to be closed for that.
It can also work with float switches...
I wouldn’t use a rain sensor for this, but rather a level sensor. Otherwise, you’ll lose water. With 3000 liters (790 gallons) there isn’t that much anyway.
If you already have backflow issues, it might also be an option to use a backflow preventer. However, the system would need to be closed for that.
F
FlorianBaaske3 Aug 2019 21:51Hi rick2018,
This is exactly what we are looking for. I will take a closer look and report back.
Best regards,
Florian
This is exactly what we are looking for. I will take a closer look and report back.
Best regards,
Florian
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