I have rain water harvesting pit which is 5 feet in depth.

During the June to October it has water for 3 feet.

November-January , it has water for 4 feet

and rest of the year it has water upto 1 to 1.5 feet.

I'm little worried about water that's stagnating here and what diseases or mosquitoes or insects it might produce.

Should I fill 2 feet with sand or coal or broken brick ? or Should I leave it as it is ?


This is a clary area and ground water level goes up , when water starts flowing in river or it's raining.


Please find the photo of rain water harvesting pit. It's 2 feet circular cement ring well with open bottom

enter image description here

  • Do you actually need that much water? If not, switching to insect-excluding rain barrels might be worth considering. If you actually do need that much water I'm not sure. Your county agricultural extension office or equivalent might be able to give you specific advice for your area.
    – keshlam
    Commented Apr 30, 2023 at 3:05
  • Don't fill it with crushed rock or anythng else. This would reduce capacity and not inhibit mosquitoes. Do you see mosquito wigglers in the water? There is a legal treatment chemical that inhibits mosquitos from progressing beyond a certain stage of development. Commented Apr 30, 2023 at 16:38
  • @keshlam - Thanks for pointing out insect excluding rain barrels , I intend to use this rain water to recharge into the earth.
    – CuriousMan
    Commented Apr 30, 2023 at 18:28
  • 1
    @CuriousMan: OK, so this is just a swale, buffering runoff until it can soak in, rather than transferring it elsewhere for use? If so, then the best suggestion might be to replace it with a dry well, not open to the surface. No bug issues.
    – keshlam
    Commented Apr 30, 2023 at 19:28
  • 1
    I withdraw my suggestion of using a mosquito growth regulator. It might cause problems for other species or contaminate groundwater. Commented May 1, 2023 at 22:20

2 Answers 2


To solve insects, screening to exclude insects.

To solve "stagnation" either an aerator or a pump so it's not stagnant.

  • 1
    Turning it into a koi pond could also reduce insects; I don't know by how much. But I have friends that would warn you it's very hard to keep a koi pond from becoming a racoon feeder.
    – keshlam
    Commented Apr 30, 2023 at 16:18
  • 2
    Mosquito fish (Gambusia affinis) would be another approach probably less attractive to raccoons and still devastating to larvae.
    – Ecnerwal
    Commented Apr 30, 2023 at 16:30
  • I've updated my question with photo. This is how my rain water harvesting pit looks like. I don't think I can use this as koi pond or I can raise mosquito fish and also How am I gonna use aerator here.
    – CuriousMan
    Commented Apr 30, 2023 at 21:36
  • 1
    Aerator is trivial. An air pump wherever convenient, and drop an air hose with a weighted end (or a rigid air pipe) to the bottom. Should be relatively easy to screen the opening and keep insects out.
    – Ecnerwal
    Commented May 1, 2023 at 0:09
  • 1
    Takes 1 air pump and hoses or pipes to 6 wells, then. If primarily concerned with insect breeding, all it takes is screening for 6 wells and don't get overly concerned with stagnation, which may be more in your own fears than in fact, given that the wells are open on the bottom.
    – Ecnerwal
    Commented May 1, 2023 at 23:49

Throw in some mosquito dunks periodically, as necessary.

  • Please edit your answer to explain what these are. Not every viewer will know. Commented May 2, 2023 at 15:06
  • @RohitGupta anyone who can use this website can also use Google (or their other favorite web search engine). Give a man a fish...
    – Huesmann
    Commented May 3, 2023 at 12:31

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