Over the last couple of years the toilets in our house were flushing slower and slower. Being a home inspector I checked many things and knew that the drains in my early 1990s home were fine it was just the toilets themselves.
Since these toilets were from before the low-flow requirement, and seeing on a daily basis how poorly many low-flow toilets worked, I was loathed to replace them; I’d rather flush once with one gallon of water instead of twice for 1.5 gallons or more thankyouverymuch.
One thing I’d fought in all of our toilets was the calcium buildup in the bottom of the bowl leading up into the trap. My wife is a clean freak so cleanliness was not the issue but our water was. The buildup would get so bad that once a year I would have to chip the calcium build up off, carefully of course, with a flat-bladed screwdriver. The problem with this is you can never get up inside the trap area so over the years that build up with cutting off the flow.
I knew there had to be some kind of cleaner or solvent that I could use to remove this calcium so I tried things like CLR and Lime-Away and even sitting overnight didn’t help. Then I found muriatic acid. After just one hour every toilet in our house was flushing like Niagara Falls.
If you have a septic system you might as well stop reading now because you CAN NOT use this cleaning method. Muriatic acid is not an option if you are on a septic system as it will kill the bacteria which make the system work, so you must use only "septic safe" methods and cleaners.
For those of you on a city sewer read on, however, there are serious safety issues to consider before utilizing this approach. Study the following steps, tips and warnings and decide if you are capable of safely using muriatic acid (known chemically as hydrochloric acid). Do not buy muriatic acid until you have read, understand, and are prepared to follow all the bottle's directions and cautions. This stuff is extremely strong! Keep it well away from children and pets.
1. Turn off the water to the toilet and flush. Use a plunger and/or a sponge and remove the water left in bowl so that the acid will clean the bowl to the bottom (including the critical jet-hole).
2. Use a clear piece of poly-film (or a clear trash bag) and tape to cover the top portion of the bowl while retaining a view of the bowl's internal rim. The tighter the seal the better. Just cover the bowl portion, do not include the seat.
3. Maximize ventilation by placing a running fan in the bathroom window to exhaust air. Also open all other windows in the home. If you have a bathroom exhaust fan, turn that on too.
4. Take off the tank cover and insert a plastic (not metal!) funnel into the overflow tube. See the "Things You'll Need" section below about the correct size of the funnel. If there is a fill tube on top of the overflow tube, carefully take that off first.
5. Wear gloves, mask and eye protection. You should also wear an apron and rubber boots to protect yourself. Also, you should have an equally protected assistant firmly hold the funnel in the overflow tube so it cannot fall out. The acid can splatter and one drip can hurt you!
6. Carefully pour acid through the funnel, fast enough that it begins to flow out of the holes in the toilet bowl rim but not so fast that the funnel overflows or falls out, as this would splash acid and be extremely dangerous. You will only need about 0.5 to 1 gallon of acid. After pouring, cover the overflow tube with a sandwich bag and rubber band, then leave the bathroom and close the door behind you. Lock the door if children are in the house and make absolutely certain they stay away.
7. After 1 hour, remove the sandwich bag and replace the fill tube to the overflow tube. (If you've chosen a weaker acid this needs to be prolonged to at least overnight.) Turn on the water and flush a few times. Extra flushes are advisable in older homes with iron drain pipes, as prolonged contact with concentrated acid will damage them. Check the rim holes for proper flow. Repeat the procedure if necessary or if there is leftover muriatic acid, because it is not safe to store this stuff around the house. This acid is so strong that it often eats through the plastic container if it is stored for a long period, and it is simply not safe to have it lying around