Recently, I had a slow drain on one of the bathroom sinks. Whenever I washed my hands at that sink, I left a pool of water in the sink slowing draining way. A long time ago a friend told me that household bleach was a simple home remedy for a slow drain. The theory is the bleach will dissolve hair that collects in a drain over time. I have used household bleach on slow drains from time to time and I seemed to get pretty good results. Will household bleach fix a slow drain? I decided to put it to the test.

What Is A Slow Drain?

First of all, I had 3 bathroom sinks, all exactly the same. I plugged each sink, filled it with cold water, pulled the plug and timed how long it took the sink to drain. Here were my results:

Sink 1: 135 seconds
Sink 2: 49 seconds
Sink 3: 11 seconds

It turns out that these sinks need to be able to drain in 75 seconds in order to keep up with the flow of water from the sink faucet. Clearly, sink #1 was nowhere near meeting that standard. Now that I had a baseline, I decided to see if using bleach on a slow drain would fix the problem.

Using Bleach On A Slow Drain: One Cup For One Hour

I started by pouring 1 cup of household bleach down the drain of sink #1 and let it stand for 1 hour. I then flushed the drain with hot water for 5 minutes. As I was flushing the drain with hot water, the water level in the sink began to rise. Clearly, the drain was still draining slowly because the drain was unable to keep up with the incoming water. After I flushed the drain with hot water, I plugged the sink and filled it with cold water. This time the sink drained in 75 seconds. While my sink still drained slowly, it was pretty clear that using household bleach on a slow drain and flushing it with 5 minutes of hot water made some progress toward fixing the problem.

Using Bleach On A Slow Drain: Two Cups For Two Hours

My next test was also on sink #1. I had taken a look under the sink and decided that one cup of bleach may not have fully filled the P-trap. I felt if I poured 2 cups of household bleach down the drain, I would certainly fill the P-trap with bleach and in a higher concentration. I also decided to leave the drain soaking for 2 hours. After two hours, I plugged the sink, filled it sink with hot water, opened the drain when the sink was full and flushed the drain with hot water for 5 minutes. Despite the fact the hot water was on, the sink drained in 85 seconds. Clearly soaking the drain in household bleach and flushing it with hot water was going a long way toward fixing my slow drain. After I flushed the drain with hot water, I plugged the sink and filled it with cold water. This time the sink drained in 42 seconds.

Using Bleach On A Slow Drain: Two Cups For Two Hours (2)

Sink #2 also seemed to drain a bit slow. So, I decided to try pouring 2 cups of household bleach down the drain and leave it there for two hours. After 2 hours, I plugged the sink, filled it with hot water, opened the drain and flushed the drain with hot water for 5 minutes. Despite the fact the hot water was still running, the sink drained in 28 seconds. After I flushed the drain with hot water, I plugged the sink and filled it with cold water. This time the sink drained in 19 seconds. Not quite as good as the sink next to it, but a nice improvement.

Will Bleach Fix A Slow Drain?

Based on my series of experiments, I would suggest:

1. Pouring 2 cups of bleach down a bathroom sink, letting it to soak for at least 2 hours and flushing the drain with 5 minutes of hot water can be a easy way to fix a slow bathroom sink drain. It is simple and inexpensive home remedy for a slow drain, so I think it should be the first thing to try when faced with a slow bathroom sink drain.

2. Since bathtub and shower drains also tend to collect hair, you should try using bleach on a slow drain. Use 2 or 3 cups of household bleach with a tub drain and 3 or 4 cups with a shower drain. Let it stand over night and flush the drain with hot water for 5 minutes before taking a shower or bath the next morning.

3. Since the accumulation of hair in bathroom drains often leads to a slow drain, pour 1 cup of household bleach down each drain, let it soak for a few hours and flush the drain with hot water once a month.

Note: Bleach should never be used on a clogged drain for several reasons:
1) The extra water in the pipes will dilute the bleach and the clog may prevent you from flushing the drain with hot water.
2) If bleach does not work, you may be tempted to use a commercial drain clearing product. Bleach should not be mixed with other chemicals (such as drain cleaner).
3) If you have to disassemble the pipes to get to the clog, you donít want to have to deal with bleach or other chemicals in the water.