How to Fix a Slow Filling Toilet

If your toilet won't fill with water, start by making sure the water supply shutoff valve behind the toilet is fully open. Then, check the supply line for kinks, bends, or visible damage. Straighten the line if it is kinked. If the line is bent or damaged, replace it.

You can test the supply line for restrictions if you have a flexible line. Shut off the water, disconnect the supply line from the bottom of the fill valve, and redirect the line into a bucket. Turn the water on carefully and observe the water flow.

There may be a blockage in the line or your incoming water supply if little or no water flows into the bucket. Contact a licensed plumber to diagnose and fix the issue.

If water flows normally from the supply line but the toilet tank is still filling slowly, the fill valve may be clogged. Sediment, minerals, and calcium buildup can restrict water flow through the valve.

Older ballcocks and fill valves can also wear out over time, leading to slower refills. If your fill valve is serviceable, cleaning it may restore normal water flow. All Korky fill valves are 100% serviceable, so you may be able to clean the valve instead of servicing it.

If your fill valve is not serviceable, damaged, or over 5 years old, replacing it is usually the easiest fix. We recommend the 2X Long-Life Toilet Fill Valve. If you already have a Korky fill valve, continue reading to learn how to service it.

If the supply line is working and the toilet tank is filling slowly, your Korky fill valve may need to be serviced. Servicing the valve can help remove trapped sediment, minerals, or debris that may be restricting water flow.

1. Turn off the water supply valve and flush the toilet handle to empty the tank of water.

   

2. Remove the refill tube from the valve cover, then pinch the cap to remove it.

   

3. Remove the valve cover by placing your thumb under the tab and lifting. The color of your Korky valve may vary by model.

   

4. Remove the float by gently pinching the float arms toward each other. The float is the piece with an "X" on the top.

   

5. Remove the cap by holding it tightly and turning it to the left one-eight of a turn. Hold the valve body in place while turning the cap to prevent the valve from unlocking. Rinse the cap under warm water to remove debris.

   

6. Remove the supply tube by pulling it straight out of the valve.

   

7. Pull the white strainer from the bottom of the supply tube. Rinse it under warm water to remove sediment.

   

8. Reinsert the strainer at the bottom of the supply tube. Then, insert the supply tube back into the valve body.

9. Twist the cap clockwise to lock it back onto the fill valve.

   

10. Reattach the float arms to the valve body. Tap the "X" on the float to make sure it moves freely and does not scrape the sides.

11. Reattach the valve cover and reconnect the refill tube. Make sure the refill tube is clipped to the lip of the flush valve overflow tube. Do not insert the refill tube down into the overflow tube; this can create a siphon and cause the valve to run continuously.

    

12. Make sure the fill valve body is locked in place by turning it clockwise.

13. Pinch the refill tube and cover together one more time to make sure the cap is fully tightened.

    

If your toilet still fills slowly and you do not have a serviceable fill valve, replacing the valve is usually the easiest fix. Older ballcocks and fill valves can wear out over time, leading to weaker water flow and slower tank refills.

Fill valves that are over 5 years old, damaged, or not designed to be serviced should be replaced with a Korky fill valve. For step-by-step instructions, follow our guide to learn how to replace a toilet fill valve.