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A toilet with a weak flush can be a major cause of frustration. If it regularly takes you two or more flushes to accomplish what a single flush should, it may be time to address the problem at its source—inside the tank. Making sure everything is up to standard will go a long way toward keeping your toilet in good working order and avoiding expensive performance issues. The first thing you should take a look at is the water level inside the tank. Assuming this is where it needs to be, you can start diagnosing other possible factors in low water power, such as clogged siphon jets or a leaky flush valve.

Method 1
Method 1 of 3:

Checking for Leaks and Damage

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  1. [1] 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. Find the shutoff valve on the wall near the base of the toilet and turn it clockwise to stop the flow of water. Then, flush the toilet to drain the tank. [2]
    • Prior to draining the toilet tank, test 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.
    • Rotate the shutoff valve until it stops turning to ensure that the water is completely off.
  2. 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. [3]
    • The majority of water flow problems can usually be traced to the components located in the tank of the toilet. [4]
    • Be careful not to drop the lid or handle it carelessly, or it could break.
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  3. 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. [5]
    • 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. [6]
    • 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. Shake it to ensure there is no water inside. If there is, it needs to be replaced or the toilet won't fill properly.
  4. 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. [7]
    • 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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Method 2
Method 2 of 3:

Raising the Water Level in Your Toilet

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  1. In order to increase the amount of water released with each flush, you’ll need to have access to the tank. Shut off the water supply, remove the lid and hit the plunger to drain the tank. Once this is done, you’ll be able to work unobstructed.
    • Do not attempt to change your toilet’s fill level while there’s still water in the tank.
  2. On most standard toilets, this 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. [8]
    • 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. [9]
    • If there’s any obvious damage to your toilet’s fill valve, the wisest option is to simply purchase a new one.
  3. If your toilet uses a ballcock design with a floating rubber ball attached to a separate arm, you can manually adjust the water level by twisting the stem at the top of the arm counterclockwise. If it uses a newer sliding cylinder construction, simply pinch the clips on the edge of the cylinder and raise or lower it to the desired height. [10]
    • You may need to use a screwdriver, coin or some other slender object to change the position of a ballcock stem.
    • For newer toilets with a sliding cylinder, the adjustment for water level is a small screw located on the top of this cylinder.
    • Take note of the normal water level, as indicated by hard water discoloration. This will give you an idea how much water is typically needed to achieve a satisfactory flush.
    • On some newer toilets, the manufacturers specify the optimal fill level with a line etched on the interior wall of the tank. [11]
  4. 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 set your toilet tank to overfill. This will cause it to run incessantly in an effort to drain excess water, which is wasteful and expensive. [12]
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Method 3
Method 3 of 3:

Clearing Out the Siphon Jets

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  1. 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.
  2. Pour in roughly ½-1 gallon of pure distilled white vinegar. Depending on the exact size of your toilet tank, you may need to use slightly more vinegar—it should be enough to totally submerge the flush valve. [13]
    • Vinegar contains mild natural acids, which makes it perfect for disinfecting and dissolving dirt and grime safely.
    • Make sure the rubber flap of the flash valve is securely closed before pouring in the vinegar.
  3. The siphon jets 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. [14] Work your way around the bowl, smoothing a strip of tape over each of the jets. You may have to use several pieces of tape to cover every last jet. [15] .
    • Over time, mold, mineral deposits and other gunk can build up in the siphon jets. This makes it more difficult for water to flow through them, and the result is a much weaker flush.
    • If you’re having trouble getting the tape to stick, try dabbing the area around the jets with a towel before applying it.
  4. As the vinegar drains from the tank, it will fill the siphon jets. With the duct tape in place, however, it will have nowhere to go. It will therefore stay in the jets, clearing them of troublesome clogs. Leave the vinegar to sit for at least an hour. [16]
    • For best results, allow the vinegar to soak the clogged jets overnight.
  5. 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 siphon jets 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 jets. You should discover that the toilet’s flushing power has improved considerably. [17]
    • Plan on cleaning out the jets of all the toilets in your home about once a year, or whenever you observe that flushing power is suffering. [18]
    • Baby bottle brushes are great for cleaning the jets.
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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.
    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

      • 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.
      • Have the toilets in your home professionally inspected once or twice a year to avoid performance issues.
      • Regularly deep-cleaning all accessible parts of the toilet will ensure that water is able to flow freely through it.
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      Warnings

      • If you’re unsure how to remove, repair or replace any of the inner workings of your toilet, play it safe and call a professional plumber.
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      Things You'll Need

      • Screwdriver
      • Distilled white vinegar
      • Duct tape
      • Stiff-bristled brush
      • Various replacement parts

      About This Article

      Article Summary X

      To increase water pressure in your toilet, try adjusting its fill valve. First, shut off the water to your toilet and flush it to empty the tank. The fill valve is usually on the side of the tank. You can adjust it by pinching the clips or twisting the nob on top, then raising it to your desired height. If this fails to improve the pressure, empty the tank again and examine the toilet’s parts to see if anything is chipped or cracked. If you spot damage, purchase replacement parts from your local hardware store and install them. For tips on how to clear out the toilet’s siphon jets, keep reading!

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      • Jeremy Neilly

        May 4, 2020

        "Thanks to this article, I can now flush the toilet again."
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