Flush tanks leaking

Before attempting to repair a toilet tank which leaks, it is necessary to understand how the water enters the tank and how it is regulated so that the tank will not overflow.


Water enters the tank through an opening fitted with a valve. This valve has a washer, so that it will completely stop the flow of water when the valve is closed. The opening and closing of this inlet valve is governed by the copper or glass float which is connected to the valve by means of a rod. The float is airtight and rests on the surface of the water inside the tank. As the water rises in the tank, the float rises with it until, at a predetermined point, the inlet valve is closed by the action of the rod attached to the float. The flow of water into the tank is thus stopped.

The handle on the outside of the tank is connected by wire rods to a rubber flush valve which fits over the opening at the bottom of the tank. This opening is connected to the toilet bowl by a section of pipe. When the flush valve is lifted from the valve seat by turning the handle, water rushes out of the tank into the toilet bowl.

As the water level in the tank drops, the float drops with it, and this action opens the inlet valve so that water can flow back into the tank. As soon as the handle on the outside of the tank is returned to its normal position, the flush valve drops over the valve seat to prevent any more water from flowing from the tank into the bowl. The tank then fills with water until the inlet valve is closed by the float's reaching a set height.

An overflow pipe inside the tank allows water to flow into the bowl, should the inlet valve fail to close at the proper time.

Keep in mind that all the mechanism inside the tank is delicate and can be thrown out of adjustment rather easily. Make sure that all the rods are working correctly before you begin replacing valves and washers.

There are several places inside the tank where a leak is likely to occur. It is possible to locate the cause of a leaky tank by removing the top and looking at the water level. If the water level is low and water is flowing out of the tank into the toilet bowl, the flush valve is not closing. If the level of the water inside the tank is high and water is flowing out of the tank by way of the overflow pipe, the inlet valve is not closing.

Leak at flush valve

A leak at this point can be caused by three conditions. A flush ball which becomes worn, rotten, or distorted in shape will no longer fit tightly over the valve seat. Rust or dirt on the valve seat will also prevent the ball from fitting evenly. The third condition occurs when the thin metal rods which connect the flush ball with the tank handle become bent or bind, and the ball cannot drop back over the valve seat.

To find which part of the system is at fault and to make the necessary repairs, you will have to shut off the water supply. Most tanks have a small valve located on the pipe running from the bottom of the tank through the floor. This is the supply line to the tank, and when this valve is closed no water will be able to enter the tank. If the tank does not have this valve, shut off the water by closing the right branch valve in the house plumbing system or by lifting the copper float inside the tank, and propping it to hold the inlet valve in a closed position.

Once the water has been shut off, you can remove the flush ball and examine it for wear. This ball is fitted with threads at the top and screwed to the rod linking it to the tank handle. If the ball is worn or out of shape, it should be replaced.

Check the flush valve seat for dirt or rust after the ball is removed. If it appears to be rough, smooth it by rubbing the rim with emery cloth. Remove any sizable pieces of scale or rust with an old knife. After smoothing the valve seat, screw the new flush ball to the connecting rod.

Test the operation of the linkage between the handle and flush ball by turning the handle to the open position and then to the close. The ball should drop on the valve seat when the handle swings closed. If it fails to do this, examine the rods to see if they are bent. The lower rod attached to the flush ball is held in place by a metal guide arm connected to the overflow pipe.

This guide arm is adjustable and should be positioned so that it is directly over the valve seat. If it is out of adjustment, the flush ball will not line up properly on the valve seat. If any metal rod is badly rusted it should be replaced, for a corroded rod will not long maintain its shape.

Leak at inlet valve

A leak due to failure of the inlet valve to close can also be caused by several factors.

It may be due to a worn valve washer or a rough valve seat. If the rod connecting the float to the inlet valve were bent out of shape, it would cause the valve to remain open, as would a leak in the copper float.

To replace a worn inlet washer, shut off the water from the tank before disassembling the inlet valve. In some tanks this valve is located near the top of the tank, while in others it will be found at the bottom.

If the latter, you will have to flush all the water out of the tank to get at the valve. The plunger of the valve is held in place by thumb screws which will probably have to be started with the aid of pliers. The washer is held in place by a nut and a brass ring cap. The ring cap may be so rusted that it will break while it is being removed. If this occurs, you will need a new cap as well as a new washer. While the valve is disassembled, check the valve seat to be sure that it is not rough or nicked.

A copper float which contains water will not rise high enough to shut off the inlet valve. You can solder a small leak in the float after draining the water out of it, but replace a float which has a bad leak.

The rod connecting the float to the valve has a great deal to do with how much water flows into the tank before the valve is closed. If the rod is bent upward, the level of water in the tank will be higher. If the rod is bent down, the water level will be lower. When a tank that is otherwise working correctly fails to deliver enough water to the toilet bowl, it is likely that the rod is bent out of shape. This takes only a moment to repair. The water level in the tank should be almost to the top of the overflow pipe. If it is too far under this point, the toilet bowl will not be flushed properly.

Condensation on tanks

A source of constant annoyance in many homes is moisture dripping off the sides of the toilet flush tank and onto the bathroom floor. This is usually a year around affair and can, in time, ruin the flooring and damage the ceiling below. A common cause of the trouble is due to the fact that the sides of the flush tank are kept at a low temperature by the fresh water entering the tank each time the toilet is flushed. This is especially the case if the fresh water supply comes from a deep well. As the air in every bathroom has a high moisture content, there is bound to be considerable condensation on the sides of the tank.

One remedy is to cover the tank with cold-water pipe insulation and to cover this, in turn, with linoleum, sheet plastic, or other material for the sake of appearance.

One homeowner solved the problem by running a hot-water line to the tank and connecting this to the inlet line. A gate valve was installed on the cold-water line and this was adjusted so that the temperature of the water in the tank remained between 70 and 90 degrees F. A check valve was also installed on the hot-water line to prevent cold water from backing into it. While the cost in materials and labour for such a job might be somewhat high, many housekeepers would gladly pay the price to get rid of this problem.

Another method is to install a small enamelled pan under the tank and connect it to bowl by a short rubber hose. Water from tank drips onto pan and runs into bowl. Such drip pans are sold in plumbing shops.

Cracks in toilet bowls and flush tanks

There is no sure way to seal a crack in a toilet bowl. Cracks in flush tanks can be mended by draining out all the water, letting entire inside get perfectly dry, and then, coating it with roofing compound.


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