Pour 12 oz. to 1/2 gallon of bleach into the drains. You can clean out all the drains at once, or do it in stages. Leave the bleach in the drains overnight. Do not pour any water through the drains. The bleach loosens and dissolves hair and sludge.
Bring two or more gallons of water to a boil for each drain the next morning before using the drains.
Pour the boiling water down the drain. This will wash away the sludge the bleach has loosened.
Sludge builds up easily in the drainpipes and it can cause the drains to flow slower, along with emitting a foul smell. Sludge is a product of different things going down the drain–toothpaste, food particles and maybe some grease. Mold and mildew can also cause sludge problems. If you use chemicals to clear away the sludge, they may eat holes in your pipes. Taking care of your drains will keep them running like they should.