How to Prevent Algae on a Condensation Drain

LESLIE: Anthony in Florida is dealing with some algae on a condensation drain. Tell us about it. Where is this drain?

ANTHONY: The drain itself – which is unusual, to my knowledge – runs down to the intake of the actual air conditioner itself, to the condenser and runs down through the foundation. And to me, it drops straight down to the main drain, because I took a wire snake – it’s just about the only thing I could get down there – and it dropped about 12 feet, so …

TOM: Wow.

ANTHONY: Yeah. Yeah, it took about 12 feet of that wire. Didn’t feel like it ran around any corners. Then again, it’s PEX pipe, so it may have just snaked through a curved S or whatnot down to the main drain.

TOM: OK. So it goes from the air handler down through the floor below? Is that what it’s doing?

ANTHONY: Yes, it does. Through the concrete foundation, yes.

TOM: Through the floor below and into the concrete foundation. Well, it’s probably just – it sounds like it’s – you don’t know where it pops out anywhere, do you?

ANTHONY: No, it does not pop out anywhere.

TOM: Yeah, it’s probably just dropping into the soil under the house; that’s what it sounds like they did to it.

So what’s your question?

ANTHONY: My question is – I managed to free up the drain tube, because I had a lot of water in my receiver. It was insane. I managed to clear that by using that wire snake and then – I wanted to know, is there an enzyme that you can put that will prevent that from happening again or is that just something I have to check every six months, say?

TOM: Yeah, I don’t think you’re going to want to treat your condensate water, which is what you’re suggesting. If this becomes an ongoing problem, I might think about a way to reroute that, perhaps add a condensate pump and have the condensation pumped elsewhere so it doesn’t gravity-drain. You could pump it up and drop it somewhere else that makes sense based on the configuration of your house. It could be up in the attic, across and out. It could be down into a floor, across and out. It could be into another drain somewhere else in the house. But if it became a real ongoing problem, I’d consider rerouting it so that you could maintain it properly.

ANTHONY: OK. Well, I appreciate it.

TOM: You’re welcome, Anthony. Good luck with that project and thanks so much for calling us at 888-MONEY-PIT.