I have a 3/4 inch PVC line that is draining from my water heater pan through an exterior wall. I want to add some bug screen to it so that no roaches or other unwanted pests crawl up it. From what I have seen online, I have to buy a massive amount of bug screen and figure out how to attach it. Is there any other way to insect proof a PVC pipe besides having to buy so much bug screen? If not, what is the best way to attach bug screen to an exterior PVC pipe?

  • Install a trap.
    – Hot Licks
    Nov 12 '19 at 0:50

Bunch the screen over the end of the pipe bent back along the nearby sides of the pipe, Then secure in place with a suitably sized screw gear clamp.

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Picture Source


I used a piece of a nylon stocking, smoothed the edges of the PVC, stretched it over the edges and gave it a few wraps of electrical tape... been there for at least 8 years.

  • 1
    This should be fine as long as it doesn't have exposure to sun or excess heat. Either of the two will cause the nylon to degrade faster though. Or if you have the kind of critters that like to chew through things.
    – Doktor J
    Nov 11 '19 at 15:36

Something similar to @michaelkaras answer is a spark arrester over the outlet.

These are used in fire-risk areas on vehicle exhausts to stop hot sparks or embers. A flat layer would reduce air flow, so fashioning a "balloon" shape. or a tube with a closed end is common and effective.

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from http://www.myrides.co.nz/4wd-car-exhaust-spark-arrestor-xidp1425177.html


A better solution may be to install a trap like this one: https://www.homedepot.com/p/Charlotte-Pipe-3-4-in-PVC-Sch-40-Condensate-Running-Bend-Trap-PVC027010800HD/204837401 ( or a P-trap).

I would be concerned that any type of screening will become clogged with sediment and impurities in the drain--which could leave you with damage due to water backing up.

  • 4
    The type of trap that you show will work if the OP were to flush water through the pipe from the water heater pan on a fairly regular basis. Normally the water heater pan should see so little water flow that this type of trap will dry out, Very similar to the problem with unused sink and unused shower drains that need to get their P-traps refreshed every so often. There are some solutions to the latter by adding some oily liquid to drain that forms a floating layer on top of the water to prevent evaporation. Not sure how that would work with the gentle bend PVC that you show.
    – Michael Karas
    Nov 11 '19 at 14:57

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