There are currently no thanks for this post. We stand by our product, every time, on time, so you don’t lose time—with industry-leading expertise. The best way to save on your combi installation is to shop around reach out to multiple engineers in your area by. Useful baking soda solutions. Pour bleach down the drain and let it sit for one hour, then use hot water to rinse it off and push down all the clogs if the clog is very compact, go for liquid bleach, but if the clog allows some.