Check valve to block mosquitos?

[MillWeld]

We collect rainwater in an underground cistern and when I remove the lid in the summer/fall there are always mosquitoes flying inside or skimming the water surface. I have used mosquito dunks for years with limited success so I am considering alternatives. The only way they can get in is through the 30' long 6" dia overflow drain so I am considering putting a check valve at the end of the pipe such as this one: ProFlex™ Style 74 Slip-In In-line Rubber Check Valves
I have to call to get a quote so I assume they are expensive because they won't sell just one. I know it is designed for backflow prevention but if it pinches closed tight enough maybe it will block mosquitoes. Any comments or ideas?

 

[mwayne]

The ones I have seen like that in use require about 10 ft. of head pressure before releasing. Didn't see a spec for the one you referenced.

 

[Ford850]

Would a P-trap work for this? Or would a screen over the outlet work?

 

[MillWeld]

There is no way to get 10 ft of head. More like 6" is all that is available.
I thought of a trap but water would evaporate from it during droughts allowing the problem to return.
Even though our gutters have screens over them a lot of small debris (including pine needles) get thru and be trapped by a mosquito screen.

 

[chim]

Would it work to tie a black plastic bag over the end of the pipe? (cut the sealed end out of it to make it a tube). It would collapse under its own weight when water wasn't flowing.

 

[coldsteelva]

I use an IBC tote as a rainwater collection barrel - I simply use a replacement fiberglass window screening material over the opening to keep out mosquitos and bird seed (dropped on the roof by birds). Simple - simple. Just wrap over the lip and zip tie.

 

[/pine]

It should not be too difficult to make your own flapper type "check" valve...starting with a 6" sched. 40 fitting...maybe a 22.5* El. to give it a slight up turn to allow gravity to keep a flapper closed when no water was running...?

Good Luck...

 

[MillWeld]

Dang good ideas, guys. I think I will use Chim's idea first until I can make a flapper valve like/pine suggested.

 

[Diggin It]

How much water? I have a 1,000 gallon cistern and used to drop a cup of regular laundry bleach in when I had it filled with spring water. Used to be the only water for this house before the public water lines were finally installed.

 

[ns_in_tex]

Why not just cut the end of the pipe on a 45, then hinge a piece of sheet metal at the top. Weight would keep it closed until water pushed it up.