ᐅ Converting an old septic tank into a rainwater harvesting cistern
Created on: 17 Apr 2023 10:00
T
tzippy84
Hello!
Our single-family house from 1966 still has an old septic tank of 7.5sqm (80.7 sq ft). It is divided into 4 chambers inside.
It was only used for 3 years (because then the sewer connection was made) and afterwards cleaned and filled with soil. This soil was partially removed by the previous owners.
I would like to use this septic tank now as a rainwater cistern for garden irrigation.
Do you think the effort is worth it? I would probably have to remove the chamber partitions somehow, so that in the end I don’t need a pump for each chamber.
I have also attached a site plan. I would like to lay a pipe directly from the downspout into the tank. Then an overflow that goes back towards the downspout but connects to the pipe leading to the soakaway. That way, water that does not fit into the cistern flows back into the soakaway, where all the water from the downspout currently infiltrates.
I would probably also have to check everything for watertightness and possibly reseal it.
All in all, it is quite a big project. Do you think it’s worth it?
Thanks for your thoughts on this.
Our single-family house from 1966 still has an old septic tank of 7.5sqm (80.7 sq ft). It is divided into 4 chambers inside.
It was only used for 3 years (because then the sewer connection was made) and afterwards cleaned and filled with soil. This soil was partially removed by the previous owners.
I would like to use this septic tank now as a rainwater cistern for garden irrigation.
Do you think the effort is worth it? I would probably have to remove the chamber partitions somehow, so that in the end I don’t need a pump for each chamber.
I have also attached a site plan. I would like to lay a pipe directly from the downspout into the tank. Then an overflow that goes back towards the downspout but connects to the pipe leading to the soakaway. That way, water that does not fit into the cistern flows back into the soakaway, where all the water from the downspout currently infiltrates.
I would probably also have to check everything for watertightness and possibly reseal it.
All in all, it is quite a big project. Do you think it’s worth it?
Thanks for your thoughts on this.
Nida35a schrieb:
One pipe is enough: a downpipe with a T-joint and a bend below leading to the cistern.
The pipe to the soakaway goes sideways from the T-joint. I’m not sure I fully understood what you meant by “bend below leading to the cistern.”
I just imagined it like in the picture. Is there any reason not to do it that way?
Tolentino schrieb:
Exactly the opposite, the branch to the sewer must be higher than the one to the cistern.
Then the water will only flow into the sewer if the cistern overflows. That’s exactly how I thought and wrote it.
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