ZepDrain Defense Enzymatic Drain Cleaner Powder - 18 Ounces - ZDC16 - Safe for Pipes and Septic Systems, Pack of 1, white

Bathroom sink was draining slowly, and occasionally there would be smell coming from the overflow, We tried standard stuff like Drain-O to no avail. As we live in an older house with older plumbing, we were hesitant to use anything stronger.So we got this product and following the directions, are now on day 2 of 3 of treatment. Already we can see an improvement in drainage. The one thing we couldn't do was take out the stopper completely; we just unscrewed the cap, cleaned out some gunk visible there, and then applied the Zep, hoping that would be sufficient. So far so good.

I've been using this for a month and so far no drain flies. When I first started I had a few but they are now gone. As it gets warmer outside it usually gets bad in my house for some reason so hopefully this will continue to work. Make sure you follow the instructions!

I'm writing this review in order to maybe help someone else that has a drain fly problem. I first saw 1-2 drain flies on my tile shower wall. I first started making my own baking soda/salt/vinegar solution and pouring down the drains. I did A LOT of cleaning of the sink and shower pipes. And, I unscrewed and cleaned out the U-pipes under the sinks. I was still seeing a few flies in the bathroom. Secondly, I tried In Vade Bio Drain cleaner (thick gel) from Amazon. Thirdly, I tried ZEP Liquid Heat Gel Industrial Drain Opener (thick gel) from Wal-Mart. Fourthly, I used Zep Drain Defense Pipe Build-Up Remover Power. This one is the best value because you mix only a small scoop with a pint of water. (I do deduct one star because of the packaging. The canister came in a brown flat paper bag like envelope. When I opened the envelope up, powder had spilled out in the bag. When I got that mess cleaned up, I discovered that the scoop was at the bottom of the canister. Other reviewers have also written this. If the canister had a thin plastic seal on the top, it wouldn't spill out during shipping even if the screw-on cap came off. That's just a suggestion for the company.) This product says - "Made in the USA". I think the two (2) Zep products were good ones. After thorough investigation of the tiled shower, which I had stopped using while fly killing, I found dead drain fly larvae around the cracked grout where the grout flooring meets the tile wall of the shower. The flies were breeding in the shower pan. I have had a fan running in the shower 4 days now. I haven't seen any drain flies in 2 days now. I ordered Tekko Trio Foam from Amazon, and that came in today. I've now sprayed that in the crack line of the grout all the way around the shower. During this whole 10 day process, I've kept the drain openings covered when not in use.UPDATE: Flies were still not completely eliminated after using multiple products, so I hired a carpenter to tear out the whole shower floor & about 4 inches up the shower wall and start from scratch to replace the shower floor. Whenever the carpenter tore out the tile on the lower 4 inches of the shower bench, 8-9 flies swarmed out. He said it looked like the drain flies had made a little cave under the shower bench. It has been a long process tearing out the shower floor and replacing it. My advice to anyone with drain flies in a tile shower is to keep going further to find the source of the moisture and fix it. Then, you will have no more flies.

This is not a replacement for Drain-o or Liquid Plumr. This is for extended use when your drain is not already clogged. Drain-o is like the ER, and this stuff is like doing exercise. It's preventive. I've used it maybe every two months for the past five years, and my drains work as well as they ever have.I will say, it is a little more finicky having to mix a powder in a cup, as opposed to the 'pre-mixed' jug type, because you need to leave a drain untreated so you can rinse out the container afterwards. It's just an extra step compared to pouring something out of a jug, but I suppose it saves the storage space.

So most people are looking at this product since your pipes are clogged and you are looking for some natural way of breaking through sludge rather than use the chemical products. I bought this product since my kitchen sink was backing up pretty bad. So the reason I gave this a three star is that I am not sure how effective this product is. Initially when I first used the product, it appears that it helped with the drainage. Unfortunately, after a few weeks later, my sink backed up to the point that I had to call a plumber. I literally dropped the powder twice (one at night and in the morning) a day and let it sit for several hours, but it didn’t help. I did look at the p-trap before calling the plumber and it appeared clean, but it appears that the sludge was behind the wall.Just to give you some insights, I live in a condominium and the clog was apparently behind the walls. I had thought it would be covered by the home owners association since it is between the walls. However, the plumber said it was my pipe and that I was responsible. So the product may work on the pipes under the sink, but not sure how much effective it is or if it is just kicking the can (sludge) down the road for you to eventually call a plumber.TL:DR – It seems like it works on the pipes below the sink, but it may just delay the problem. Had to eventually call a plumber since it didn’t clear the clog beyond the wall.