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What are the Causes and Fixes for Toilet Tank Not Filling?

A toilet tank not filling is a major problem for anyone, from single-family homeowners to the managers of large New York City properties. This is a service call we see frequently at Sanitary Plumbing, but sometimes there are fixes you can do that save you from having to call the pros. Here are nine common causes for a toilet tank not filling, many of which you may be able to remedy on your own.

No Water Supply

What to check

This might seem like a no-brainer, but your toilet needs a water supply to function. If the supply is cut off anywhere along its route, the toilet won’t fill as it should. First, check to ensure the valve beneath your toilet isn’t shut off by accident. If you’ve had work done in the bathroom, it might have been put in the closed position. Also, sometimes kids play with these valves to see what they do.

Try turning on the water in your bathroom sink. If there is no water there either, the problem is further upstream. Check the water supply to your home or building and make sure you are receiving municipal water (it could be blocked where it enters, or the city may have turned it off temporarily for work in the area). If water is entering the home but not reaching your bathroom, the problem is probably a blockage or leak in your interior plumbing system.

Low Water Pressure

Multiple causes

Sometimes pressure can be so low that it’s like not having any water at all. As above, this could be a water supply issue. It could also mean your water pump is malfunctioning, especially if this is happening to multiple tenants in the same building. If you have a very tall building, you may experience lower water pressure at the upper levels. This requires service from a pump specialist, who can install a booster pump.

Broken Trip Lever Assembly

Fix accordingly

When the trip lever assembly for your toilet fails, usually the part just inside the tank that connects to the handle has corroded and become disconnected. You’ll see this by removing the lid to the tank and examining the interior. This problem is usually easily fixed with a trip to the hardware or home supply store.

If this is your first toilet repair, snap a few pictures with your phone so you can show sales staff what your problem is. They can direct you to the right parts and offer some basic instruction. And of course, you can always call a plumber to do the repair, as they’ll have the parts and tools to get the job done quickly and correctly.

Fill Valve Maladjustment

Tighten or loosen

It’s a good idea to acquaint yourself with an illustration of the basic parts of a toilet. The fill valve is a tube assembly that tells the toilet when to fill and stop filling. First, give it a look to make sure there is no debris inside the tube and that the tube itself is intact with no leaks.

Fill valves have different anatomies depending on the age and make of the toilet. You may be able to make an adjustment to the valve to fix your toilet that won’t fill.

If your fill valve has a screw on top, you can try adjusting it with a flat-head screwdriver. Turning it clockwise allows more water in. Conversely, turning the screw counterclockwise restricts the water flow into the toilet.

Sometimes there is a clip on the side of the fill valve, rather than a screw on top. Pinching the clip and sliding it upwards increases the amount of water required to fill the valve, while sliding it downward decreases the required amount of water.

Float Ball or Arm Not Working

Adjust or replace

Many toilets in operation today still use a float ball and arm system to guide the fill valve. If either of these components are not working right, your toilet may fail to fill.

Occasionally, the ball itself has become so worn that it develops a leak and ceases to float properly. In that case, replace the float ball with a new one.

More frequently, adjusting the float arm will allow more water to enter the tank and the toilet to fill properly. Simply bend the arm slightly upward to raise the ball to the desired level. You may have to play with it a bit to get the right level. Some float arms also have a screw adjustment that you can manipulate as well.

If the arm is broken (often at the opposite end from the ball) it may need to be replaced. Fortunately, there are inexpensive kits available at hardware and home stores, and you can make a DIY fix.

Worn or Poorly Fitting Flapper Valve

Repair or buy another

The flapper valve is a rubber valve that sits at the bottom of your toilet tank. Its job is to keep the tank water from emptying into the toilet when it’s not being flushed. If it’s held in place by a small chain, make sure the chain isn’t caught underneath the valve, which would prevent it from sealing tight. Sometimes the chain needs to be repaired or shortened.

Often the flapper valve gasket has become worn or hardened, and it must be replaced. Depending on your comfort level, you can do this job yourself too, or you can ask your plumber to do it for you. It’s usually best to buy a few flapper valves if you plan to replace it, in case you can’t find an exact match and need to experiment. There are a few called “universal” flapper valves that also might do the trick.

Pro tip: your toilet’s flapper valve, float arm assembly, and fill valve are also places to look first if your toilet won’t stop running.

Cracked Toilet Bowl

Replace ASAP

A cracked toilet bowl with a slow leak can keep your toilet from filling, as the water keeps leaking out as the bowl fills. This can happen without you noticing if the crack is on the back of the bowl out of eyesight, although usually you’ll observe water on the floor.

If your toilet bowl has a crack, shut off the water supply using the valve beneath the toilet or the valve supplying water to the bathroom. Do not use the toilet or allow it to fill any more! Not only could it collapse under a user, it could flood your bathroom with water. If there is a room or tenant below the bathroom, that area could become damaged as well.

If you try all these fixes and you still have a toilet tank that is not filling, or if you’d prefer to have an expert do your toilet repairs, Sanitary Plumbing is here for New York City property owners. We even offer emergency 24/7 service. Just give us a call at 212-734-5000 or use our easy online form to schedule an appointment. We’ll get your toilet back to normal in no time.