How to Fix the Water Pressure in a Toilet

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Simple DIY fixes to increase your toilet’s water pressure

Co-authored by James Schuelke and Amy Bobinger, BA

Last Updated: January 23, 2026 Fact Checked

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• Checking for Leaks and Damage
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• Raising the Water Level
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• Cleaning Siphon Jets & Bowl Ports
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• When to Call a Plumber
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• Video
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• Expert Q&A
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• Tips

|Show more |Show less

If your toilet takes a long time to fill, or you regularly have to flush two or more times to get a full flush, you may have low water pressure in your toilet. Fortunately, most toilet repairs are pretty easy DIY fixes. We talked to professional plumbers James Schuelke and Dave Jones to find out everything you need to know about increasing the water pressure in your toilet, including checking for leaks, raising the water level, and cleaning out the siphon jets and bowl ports. Let’s get started!

How to Fix Your Toilet’s Water Pressure

To increase the water pressure in your toilet, adjust the height of the float attached to the fill valve. If you have a ball-style float, turn the adjustment screw clockwise. If you have a slider-style float, pinch the clip and slide the float upward. You may also need to clean the siphon jet and bowl ports.

Steps

Section 1 of 4:

Checking for Leaks and Damage

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1. 
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   Turn off the water to the toilet. Before you get started, you’ll want to make sure that there’s no water running to your toilet while you’re examining it or making adjustments. To turn off the water, Schuelke says to “shut off the angle stop, or the valve that’s directly below or behind the toilet tank.” Turn the valve clockwise, or to the right. Schuelke says to “give it a little snug to the right when it stops to make sure it’s completely off.” Once you’re sure the water is off, flush the toilet to drain the tank.

   • Before you turn off the water: Check whether the valve is open all the way. If it’s partially closed, that could be the reason your tank has low water pressure. Turn the valve all the way counterclockwise, then flush a few times to see if that fixes the problem.
   • Dye test for leaks: Prior to draining the toilet tank, Jones recommends testing for possible leaks by squeezing a few drops of food coloring into the tank and checking back the following morning. If the water in the bowl has changed colors, it means you’ve got a leak. Repairing the leak may restore your water pressure.

   Meet the wikiHow Experts

   James Schuelke and his twin brother David are co-owners of the Twin Home Experts, a licensed plumbing, leak detection, and mold inspection company in Los Angeles, CA.

   Dave Jones is a professional plumber and the Midwest Regional Vice President at Roto-Rooter Plumbing & Water Cleanup.
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   Remove the toilet tank lid. Lift the lid carefully off the back of the toilet and rest it on a flat, stable surface. You should now have an unobstructed view of the inner workings of the toilet. From here, you can start searching for the culprit of a weak flush or low overall water level.

   • The majority of water flow problems can usually be traced to the components located in the tank of the toilet.
   • Be careful not to drop the lid or handle it carelessly, or it could break.
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   Inspect the toilet’s internal flushing mechanisms. Take stock of each of the individual pieces in the tank. Look carefully for any signs of cracking, chipping, warping, or tearing. Gradual wear can eventually lead to leaks and improper filling. When these issues occur, it can cause malfunctions in the toilet’s flushing action.

   • While the toilet tank contains many small parts, your attention should be focused on the two main components: the fill valve and the flush valve. The fill valve is a narrow vertical tube that refills the tank, while the flush valve is an opening at the bottom of the tank fitted with a rubber or plastic flapper on a chain that releases water when the toilet is flushed.
   • Pay particular attention to the condition of the ballcock arm (balloon-like rubber ball on the fill valve that gauges the water level), and the chain on the flush valve. If you see damage to either part, or if there’s water inside the ballcock arm, replace them.
   • Look for the hose running from the fill valve to the overflow tube. Check that the tube is positioned so water will run directly into the overflow tube. If it doesn’t, water will fill the tank, but not the toilet bowl.
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   Repair or replace faulty parts. After identifying the part responsible for the feeble flush, make a note of its exact specifications, then take a trip down to your local home improvement store to purchase a replacement. You can attempt to put in the new part yourself by following a basic instructional guide, or call a plumber, who will have the part you need along with the know-how to install it professionally.

   • Broken and damaged parts should always be replaced as soon as they’re brought to your attention to avoid more extensive repairs later on.
   • Only buy parts that are compatible with the model of toilet you're repairing.
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Section 2 of 4:

Raising the Water Level in Your Toilet

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1. 
   1
   Turn off the water and empty the toilet tank. Schuelke says that if the water level in the tank is too low, there won’t be enough gravity to get a full flush. To adjust the water level, start by shutting off the water supply. Remove the lid if you haven’t already, then hit the plunger to drain the tank and bowl. Once this is done, you’ll be able to work unobstructed.

   • Leaving the water on can cause spills, so it’s best to turn it off for this process.
   • Before you turn off the water, pay attention to how much water is in the tank. Specifically, note where the water level is on the overflow tube. Ideally, it should come to ¹⁄₂ in (1.3 cm) below the rim of the tube. This will give you an idea of how much you’ll need to adjust the fill valve.
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   Locate the fill valve. On most standard toilets, the fill valve will appear as a large upright tube positioned on one side of the tank. This is the part that controls how much water enters the tank when the toilet refills. Your toilet’s fill valve will most likely have either a ballcock or floating cylinder construction—both can be tweaked manually in just a couple of minutes.

   • Ballcock valves make use of a floating rubber ball to gauge the water level, while cylinder valves can be set to designate the cutoff point.
   • If there’s any obvious damage to your toilet’s fill valve, the wisest option is to simply purchase a new one.
3. 
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   Adjust the fill valve so water is ¹⁄₂ in (1.3 cm) below the overflow tube. Using the water level you noticed earlier as your guide, raise the fill valve so the water level in the tank will be higher. This should increase the water pressure (and the flushing power) of your toilet. Here’s how to do it:

   • If your toilet uses a ballcock design (floating rubber ball attached to a separate arm): Manually adjust the water level by twisting the stem or screw at the top of the arm clockwise. You may need to use a screwdriver for this.
   • If your toilet uses a newer sliding cylinder construction: Pinch the clips on the edge of the cylinder and raise or lower it to the desired height.
   • If you have an adjustable fill valve: Turn the locking ring on the base of the fill valve to unlock it, then pull straight up to raise the height of the fill valve. Be sure not to raise it so high that it touches the tank lid.
   • On some newer toilets, the manufacturers specify the optimal fill level with a line etched on the interior wall of the tank.
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   Test the toilet’s flush. Turn the water supply to the toilet back on and wait for the tank to refill. Lift the toilet seat and flush. If you’re satisfied with the flush, replace the toilet tank lid and continue using your toilet as usual. If not, continue adjusting the height of the fill valve to improve the flushing power to your liking.

   • It may take you a few unsuccessful tries before you finally get the water level exactly where you want it.
   • Be careful not to raise the fill valve so much that the tank will overfill. This will cause it to run incessantly in an effort to drain excess water, which is wasteful and expensive.
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Section 3 of 4:

Clearing Out the Siphon Jet and Bowl Ports

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1. 
   1
   Clean the toilet bowl thoroughly, including the siphon jet. The toilet siphon jet sits at the bottom of the bowl, in the front of the hole. This jet can get clogged with mineral deposits, leading to slow flushing and refilling. Use an old toothbrush to clean out this port (be sure to wear elbow-length gloves for this). Just scrubbing is usually enough to start breaking up the deposits—vinegar will help dissolve any remaining residue later.

   • Scrub the rest of the toilet bowl as well, including the underside of the rim.
2. 
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   Shut off the toilet’s water supply. Locate the shutoff valve and turn it clockwise to cut off the water flow to the toilet. Remove the toilet tank lid and set it aside.

   • Since your toilet will be out of commission for half an hour or more while you clean it, schedule the project for a low-traffic time so that it won’t be an inconvenience.
3. 
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   Empty and dry the toilet bowl. Schuelke says the best way to completely empty a toilet bowl is to flush the toilet first to get any residual water out of the tank. Then, “use a wet shop vac to extract the remaining water from the bowl.” If you don’t have a shop vac, use old towels to remove any water that’s left in the bottom of the bowl. Go back over the bowl once more with another old, dry towel.

   • Be especially sure to dry the area under the rim very well—the duct tape won’t adhere if it’s dirty.
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   Place duct tape over the bowl ports. The bowl ports are the small openings around the rim of the toilet bowl that release the water from the tank into the bowl when the toilet is flushed. Work your way around the bowl, smoothing tape over each of the ports. Since the toilet bowls are curved, it’s usually easiest to work with pieces of tape that are around 4–6 in (10–15 cm) long.

   • Over time, mold, mineral deposits, and other gunk can build up in these ports. Schuelke says, “If the bowl ports are full of calcification, that restricts the water flow from going into the bowl, which is going to cause a very low flushing toilet.”
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   Fill the overflow tube with vinegar. Pour in roughly ¹⁄₂ US gal (1.9 l) of pure distilled white vinegar. Vinegar contains mild natural acids, so it’s a great option for disinfecting and dissolving dirt and grime safely.

   • As the vinegar drains from the tank, it will fill the bowl ports. With the duct tape in place, however, it will have nowhere to go. It will therefore stay in the ports, clearing them of troublesome clogs.
   • Leave the vinegar to sit for at least an hour, or up to overnight.
   • Some of the vinegar will probably leak out of the tape and sit in the bottom of the bowl. That’s fine—it will finish cleaning the siphon jet.
   • Avoid using bleach for this, as it can damage the mechanisms inside your toilet.
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   Remove the tape and clear the ports. After ample time has elapsed, peel off the strips of tape and turn the water to the toilet back on. Scrub the area around the bowl ports vigorously with a stiff-bristled brush to clear away any remaining surface buildup. Then, flush the toilet a couple of times to get water moving through the ports. You should discover that the toilet’s flushing power has improved considerably.

   • Plan on cleaning out the ports of all the toilets in your home about once a year, or whenever you observe that flushing power is suffering.
   • To keep the ports clean, Schuelke recommends putting a few drops of dish soap in your toilet tank every so often to help remove calcification. You can also use a bottle brush or even a small Allen wrench to clear them out.
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Section 4 of 4:

When to Call a Plumber

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1. 
   Call in a pro if you can’t fix the issue yourself. You probably need to bring in a plumber if your toilet still fills slowly after you’ve checked the water pressure to the toilet, inspected for leaks, adjusted the water fill level, and cleaned the jets. The problem could be a blockage in the trapway between the overflow valve and the toilet bowl, or it could be an issue with the fill valve.

   • If you can’t fix the problem and would rather not hire a pro, new toilets are fairly inexpensive, and you can install one yourself.

Expert Q&A

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• Question

  Why isn't my toilet flushing at full strength?

  

  James Schuelke
  Professional Plumber

  James Schuelke, along with his twin brother David, is the co-owner of the Twin Home Experts, a licensed plumbing, leak detection, and mold inspection company based in Los Angeles, California. James has over 32 years of home service and business plumbing experience and has expanded the Twin Home Experts to Phoenix, Arizona and the Pacific Northwest.

  

  James Schuelke

  Professional Plumber

  Expert Answer

  There may not be enough water in the tank when you flush, so you can try adjusting the fill level. Otherwise, the siphon jets around the toilet rim may be dirty or clogged. Giving them a good cleaning should help.

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Tips

• Regularly deep-cleaning all accessible parts of the toilet will ensure that water is able to flow freely through it.
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• Some problems may be the result of a poorly installed piece. Try taking a failing piece apart and reassembling the various components, making sure that everything is properly sealed and aligned.
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• If the toilet flushes slowly but fills normally, it could be a clog. Try to unclog the toilet with a plunger or plumber’s snake, or pour hot water into the bowl.
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