Your toilet flushes
just fine, but it doesn't know when to quit. Perhaps it stops running and then
starts up again suddenly or constantly leaks into the bowl. Either way, it's
wasting a lot of water and making that noise that keeps you up at night. Fortunately,
it's usually not difficult or expensive to repair a toilet if you know a bit about how they work. Be
systematic about tracking down the problem. There are only so many things that
can go wrong inside a toilet tank.
Get to know what's in your toilet. Mechanisms vary, but they all work on the
same principles. Flush a couple of times while you watch in the tank with the
tank lid off and notice the process.
Inside the tank, left
to right: valve and float, fill tube, overflow tube and flapper. Handle connects
to lever and chain.
o When you push the handle, the chain lifts a
flapper, letting a tankful of water fall through the opening in the bottom,
into the bowl. As the water level drops, the flapper drops and closes the
opening.
o A plastic float drops as the water drains. The
float is connected to a valve that lets water into the tank when the float is
down and stops (or should stop) when the float is up.
o In the middle, there's also an overflow tube
that drains water out into the bowl if it gets too high.
Catch it in the act. If you've waited long enough after flushing and the toilet
hasn't quit running, lift the tank lid and look in.
3. 
3
Close the flapper. If the tank is not full and it is not filling, chances are
that the flapper is stuck open.
The flapper in this
toilet is green, attached to a chain.
o Reach in and close it with your hand. If it
sticks repeatedly, look for the cause. Make any necessary adjustments.
§ Is the chain catching on something or is the
flapper catching on the chain? Try threading the flapper chain through a
plastic soda straw to prevent a long chain from getting stuck on things and
preventing the flapper from seating properly. Or, replace the chain completely
with a loop made from dental floss that is the same length as the chain.
§ Is the flapper wedged open on its hinge?
§ Is the flapper aligned with the opening?
§ If you have a ball seal instead of a flapper,
is the wire that lifts the ball straight and does it move freely?
4.
4
Check if the water in the tank is at the water line. Not having enough water in the tank will
have the toilet run.
o If the water is NOT at the water line, check
your water valve to see that it is on all the way. If it is NOT, turn it all
the way on and your tank should start filling up to the water line (unless the
Refill Valve or Float are not adjusted correctly). Try this BEFORE changing
flapper or anything else.
Try adjusting the valve and float.
o Pull up on the float with your hand. If this
action stops the flow, then adjust the level of the float so the tank stops
filling when the water is about an inch (2.5cm) below the top of the overflow
tube. If the tank level is too high, the excess pressure can cause water to
leak through the flapper into the bowl (even with a brand new flapper).
o If the float is around the valve post, pinch
the metal clip and slide the float down on the wire.
Pinch this clip to
adjust the float height.
o If the float is a ball on an arm, try turning
the small screws on top of the valve. Sometimes, you can also bend the arm further
down.
On this style valve,
tighten (clockwise) the blue screw or try bending the rod down.
o Make sure the float ball isn't touching
anything else. Adjust it so it isn't dragging against the side of the tank, the
overflow tube, or anything else.
o Depending on the design of the float mechanism
and how it relates to the fill tube, the fill tube can occasionally go over the
float mechanism and hold it down. Don't move the fill tube while the toilet is
filling; you may be in for a wet surprise.
o A waterlogged float can cause overflowing
(even if the valve itself is functioning properly) so make sure the float ball
isn't leaking or filling with water. If you unscrew the float ball and hear
water inside when you shake it, replace the float ball.
o If the ball valve and assembly are covered in
limescale then you could try cleaning (descaling) them (suggest you remove them
from the tank 1st). It only takes minutes and is well worth the effort. If you
have the ball valve out but cannot get it apart to get at the valve washers its
often the limescale that's gluing it together.
o If pulling the float up gently to the top of
its travel does not stop the toilet running and you've tried everything
above,you may have to replace the whole refill valve assembly. Replacing the whole
valve is a bit more of a project, so check the other possible causes and
remedies thoroughly first. If you think you need to replace the valve, it is
manageable by one person and not too expensive. Ask for advice at your hardware
store, and read the directions carefully that come with the replacement valve.
Clean or Replace the flapper and/or flush valve. If the toilet stops filling and then starts
again intermittently or water constantly runs into the bowl, you have a slow
leak from the tank into the bowl. Place a dye tablet or a few drops of food
coloring in the tank. Your local hardware store may have free dye tablets for
this purpose. If, after an hour or two without flushing, you see this dye in
the bowl, you have a slow leak, a small amount of water running into the bowl.
o The most common cause of slow leaks is a leaky
flapper. Over time, this inexpensive rubber part may decay or get old and stiff
to the point that it needs replacing, or minerals may build up on it and/or the
rim of the flush valve where it seats.
o If the flapper is still in good shape,
sometimes all it takes to make it work is to clean it &/or the rim where it
seats.
§ Run a finger carefully around the underside of
the flapper and the rim where it seats. Remove any uneven buildup of minerals
that might cause a leak. Use a sponge with bleach or steel wool or #500
wet-or-dry abrasive paper.
o Cleaning may work to remove mineral buildup,
but it's usually best just to replace the whole part. There are a few standard
kinds, so take your old one with you to the hardware store for comparison (to
ensure you get the right kind). To perform a replacement:
§ 
Close the valve
sticking out of the wall under your toilet tank by turning it clockwise, as you
would a faucet.
Close
the water valve and flush the toilet. If the valve is completely closed, the
tank will not refill and you will not hear water running after the tank
empties.
§ Pop the old flapper off its hinges, disconnect
it from the chain, and pop the new one into place.
§ Don't forget to open the valve all the way
when you're ready for water again.
§ Try flushing a few times to make sure the
chain is the right length for the new flapper. It should open when you push the
handle and then drop closed all the way when the tank empties. You may have to
trim and adjust the chain by trial and error. Also, make sure that the flapper
aligns properly with the opening.
o The small rubber fill tube leading from the
valve to the overflow tube and sometimes the valve itself can act as a siphon.
In that case, adjust the valve height or tube height up, or adjust the water
level down.
o The valve itself will not stop the water
completely. Some valves can be opened and the rubber seals replaced. If not,
you may need to replace the whole valve.
o One or more of the non-rubber components may
break in the toilet's water valve mechanism, such as the lever connected to the
plastic ball that shuts off the water by pressing down on a button as the water
level rises. If this happens, the best course of action is to buy a replacement,
but super glue can work temporarily in some situations.
o The water pressure at the small rubber fill
tube leading to the overflow tube may be too high, preventing the flapper valve
from seating. Turn the shutoff valve at the wall partially closed.
- If you notice the leak in the middle of the night or
some other time you can't get to working on the problem right away, close
the shutoff valve to avoid using excess water. Post a note nearby that the
water is shut off temporarily, and can be turned back on to fill up the
tank if needed, to avoid panicking your guests.
- If you must replace the refill or flush valve, first
shut off the main inlet valve, and then flush the toilet fully, which will
*almost* empty the tank. Keep an old towel handy and a large cup to catch
any residual water in the tank when you unscrew the valve post from its
hole in the bottom of the tank. Obviously not heeding these precautions
will produce a big mess on your bathroom floor.
- Every few weeks or months pour 1/2-3/4 cup of ordinary
bleach into the tank this way: Get ready by having the bleach handy.
Remove the tank cover, have the bleach ready to pour then flush. When
flapper drops and seals with that familiar "plunk" pour in the
bleach. The swirling action from the filling will thoroughly mix the
bleach and incoming water. This will clean up slime and other fungal
buildup in the tank and on the flapper.
