I have a precast concrete box like the one in below and this have three inlets and one outlet.

enter image description here

  • outlet -> Takes the water to near by canal
  • Inlet 1 -> Kitchen sink outlet is connected with this
  • Inlet 2 -> Bathroom drain outlet is connected with this.
  • Inlet 3 -> As of now it's not is use.

I'm thinking of connecting the septic tank overflow pipe to the 3rd inlet.

But are there any health risks associated with this ?

Just wondering if pathogens , virus , bacteria etc.. can crawl through kitchen , bathroom line and cause health issue ?

Or is there any disinfectant tablet that I can drop into the box and that would take care of the germs ?


Neither bathroom nor kitchen line has P trap so far , I think point of having p or s trap is to stop the toxic gas from coming in but I don't have gas issue.. the water seal in the trap is not gonna handle germ issue anyways right ?

Someone please help me understand.

  • 4
    Your location in the world will help a bit. In most places dumping/draining that water into a canal/water course will be illegal. P-traps prevent sewer gas smells from coming up from the drain pipes/tanks.
    – crip659
    Apr 7, 2023 at 21:11
  • "Just wondering if pathogens , virus , bacteria etc.. can crawl through kitchen , bathroom line and cause health issue ?" I'd be more concerned about septic overflow going into a canal.
    – JACK
    Apr 7, 2023 at 21:23
  • I worry about snakes, the other stuff a doctor can handle.
    – crip659
    Apr 7, 2023 at 22:21
  • That will depend how do you isolate Normally you would not mix those two togethe Cross contamination is a problem
    – Traveler
    Apr 8, 2023 at 1:20
  • 1
    If you just piped your septic overflow in there, how would you ever know when the septic fills up and needs to be pumped?
    – brhans
    Apr 8, 2023 at 6:41

1 Answer 1


In NZ, the overflow from the septic tank must not go to waterways. It must be spread on land with vegetation where it can evaporate and be further processed by microbes. I would think the regulations are the same where you are. Please check first.

In 1995, when we got our first system, they were advertised that you could drink that water. But my supplier refused to drink it. That bravado faded quickly.

If you did take it to waterways, as one of my friends has, you will probably find that it will start looking yucky and stink. The pathogens are a problem, but so is the fact that it is nutrient rich.

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