Toilet Not Filling With Water: Common Causes and Easy Fixes

Why Your Toilet Isn't Filling or Flushing

If your toilet not filling with water is the problem you're dealing with right now, you're not alone. This was one of the most frequent problems I encountered during my time as a working plumber, and it's also one of the simplest to fix. In most toilets, water enters the cistern through the supply line, passes through the fill valve, and is cut off when the float reaches the correct height. So, when your toilet won't fill, it's often because one of these three components is faulty. If your toilet is constantly running, it's the opposite problem, as there's a fault with the fill valve or the flapper, so water won't shut off. Before calling a plumber, go through this list of common causes. Chances are the problem is something you can repair with a few basic tools and a quick trip to the shops.

Checking the Water Supply Line

The supply line is the braided hose that connects the shut-off valve on the wall to the bottom of your toilet cistern. I've seen plenty of supply lines that got kinked when someone shoved the toilet back into place, shut-off valves someone turned without realising, and corroded connections that developed over time. First, check the shut-off valve. It's usually a small tap or lever near the floor behind the toilet, and you should turn it anti-clockwise until it stops. Sometimes that's the only thing wrong. Next, inspect the supply line. Run your hand along the length of the hose to check for kinks or swellings. If the hose is old and corroded, go ahead and replace it. A new braided stainless steel supply line will cost you about $15 to $20.

Fill Valve Problems and Adjustments

The fill valve is the tall plastic device inside your toilet cistern that controls the water flow. What is a toilet cistern without a working fill valve? You don't have a functioning toilet. If your toilet not filling with water is caused by a faulty fill valve, you'll probably notice your toilet filling very slowly or not at all even when you've got good water flow at the supply line. To check your fill valve, take the lid off the cistern and flush the toilet. Water should flow into the cistern as soon as the toilet starts to flush and should stop when the float reaches the water line marked on the cistern. If the fill valve doesn't fire, the valve is probably jammed or damaged. Most modern fill valves include an adjustment mechanism on top, clockwise to lower the water level, anticlockwise to raise it. The water level should be about 25mm below the top of the overflow tube. If adjusting the fill valve doesn't work, you can buy a universal fill valve for $20 to $40. Most homeowners should be able to fit one in about half an hour.

Flapper Issues and Replacement

The flapper is the rubber valve at the bottom of your cistern. When you flush the toilet, it lifts to allow water to flow into the bowl, then falls back into place to seal the cistern. Over time, the rubber on the flapper deteriorates, meaning the valve won't seal properly anymore. This is the number one reason for a toilet running constantly. If you want to know how to fix running toilet problems, I always start with the flapper. You can test yours by adding a few drops of food colouring to the cistern water. Wait 15 minutes and don't flush. If you see the colour in the bowl, you have a leaky flapper. Replacing a flapper is a five-minute job. Turn off the water, flush to empty the cistern, unhook the old flapper from the overflow tube and clip on the new one. Universal flappers cost $8 to $15. Make sure you buy the right size for your toilet. Most Australian toilets use either a 50mm or 75mm flapper.

Troubleshooting Low Water Pressure

If your toilet not filling with water is a pressure issue and not a faulty valve, here are a few things to consider. First, is the low pressure confined to your toilet? Turn on your bathroom tap and check the water pressure. If it's also weak, you have a pressure problem with your mains supply. Contact your local water authority or a licensed plumber to inspect your pressure regulator. If the pressure is normal in other outlets, your problem is likely a blocked fill valve inlet filter. Over time mineral deposits will build up, particularly in areas with hard water. Remove the supply line and inspect the filter screen at the bottom of the fill valve. Use an old toothbrush and some white vinegar to clean it. When the cistern itself has reached the end of its life or the working parts have, it might be time to install a new one. Look for WaterMark certified toilets for sale that meet Australian standards. You should be able to find a good quality toilet for sale for less than $400.