5 Common Low Flow Toilet Problems and How to Fix Them

by Jessica Sawyer | Toilets

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Are you experiencing low flow toilet problems? Don’t worry – it’s common. While they may help conserve water and reduce your utility bills, low flow, or low flush, toilets are not without their drawbacks. Because of their design, they’re more prone to certain toilet-related problems than their traditional counterparts, which can be frustrating when it comes to bathroom time.

But there’s some good news here: fixing low flush toilet problems doesn’t have to cost you an arm and a leg. In fact, you may even already have the equipment you need to fix them yourself!

In this blog post, we’ll explore five common problems associated with low flow toilets and provide step-by-step guidance on how to fix them. Whether you’re a DIY enthusiast or new to handling plumbing issues, we’ve got you covered.

1. Clogging

One of the most common issues with low flow toilets is clogging. Unlike traditional toilets, low flow models use less water per flush (only about 1.6 gallons vs up to 7) which can sometimes lead to waste not being fully cleared.

If a clog is the problem, then you may be experiencing one or more of the following:

  • Partial Flush: If the toilet bowl doesn’t completely empty after flushing, you might have a clog.
  • Slow Drain: Water drains slowly, signalling a blockage somewhere in the system.

How to Fix a Low Flow Toilet Clog

Now that you’re sure it’s a clog, here’s how to fix it:

Tools Needed:

  • Plunger
  • Toilet auger (snake)
  • Rubber gloves


  1. Use a Plunger: Place the plunger over the toilet drain and push down gently to create a seal. Then, pump the plunger up and down vigorously. This should be enough to clear minor clogs.
  2. Try a Toilet Auger: If plunging doesn’t work, insert a toilet auger into the drain. Turn the handle clockwise to break up the clog. Be gentle to avoid damaging the toilet, as an auger can scratch the bowl.
  3. Flush to Test: Once the clog is cleared, flush the toilet to ensure it’s working correctly.

2. Weak Flush

A weak flush means the toilet is still working, it just isn’t doing a great job of clearing the waste. This is often due to low water pressure or blockages.

With a weak flush, you may experience:

  • Incomplete Flush: The toilet doesn’t fully clear the bowl with each flush.
  • Low Water Level: Check the water level in the tank; it should be about an inch below the overflow tube.

How to Fix a Weak Flush on a Low Flush Toilet

Ready to restore flushing power? Follow the steps below.

Tools Needed:

  • Screwdriver
  • Cleaning brush


  1. Adjust the Water Level: Open the tank lid and find the float. You may need to adjust it higher to allow more water into the tank.
  2. Clean the Rim Holes: Use a cleaning brush or screwdriver to clean the holes under the rim of the toilet bowl. Mineral deposits can block these holes, reducing water flow.

3. Phantom Flushing

Phantom or ghost flushing occurs when the toilet randomly refills as if it’s been flushed. The cause of this one isn’t as obvious, but it’s likely due to a slow leak from the tank to the bowl.

Some common signs of ghost flushing include:

  • Refill Sound: Listen for the sound of water refilling the bowl, even when the toilet hasn’t been used.
  • Water Movement: Look for ripples in the toilet bowl when the toilet is not in use.

How to Fix Phantom Flushing in a Low Flow Toilet

If phantom flushing is your low flow toilet problem, then there’s a good chance you’ll need to replace the flapper.

Tools Needed:

  • Replacement flapper
  • Sponge
  • Rubber gloves


  1. Turn Off the Water Supply: Locate the shutoff valve behind the toilet and turn it clockwise to stop the water flow.
  2. Drain the Tank: Flush the toilet to empty the tank.
  3. Replace the Flapper: Remove the old flapper and install a new one. Make sure it creates a proper seal to prevent leaks.
  4. Turn the Water Back On: Turn the shutoff valve counterclockwise and let the tank refill. Test by flushing the toilet.

4. Refilling Issues

Refilling issues can stem from a faulty fill valve, causing the tank to fill slowly or not at all.

Look out for these signs if you think you’re having refilling issues:

  • Slow Refill: If the tank takes too long to refill after a flush.
  • No Refill: The tank doesn’t refill at all.

How to Fix Refilling Issues on a Low Flush Toilet

In this case, your low flush toilet may need a new fill valve.

Tools Needed:

  • Replacement fill valve
  • Adjustable wrench


  1. Turn Off the Water Supply: Shut off the water supply to the toilet.
  2. Remove the Old Fill Valve: Unscrew the water supply line from the old fill valve and remove it.
  3. Install the New Fill Valve: Insert the new fill valve into the tank and secure it with the nut. Attach the water supply line.
  4. Test the Refill: Turn the water supply back on and let the tank refill. Adjust the fill valve as needed to reach the correct water level.

5. Leaks

Leaks can occur around the base of the toilet or from the tank. While you will want to rule out any non-toilet related possibilities (after all, there’s no shortage of water in a bathroom), it’s typically due to worn-out seals or bolts.

When looking for low flow toilet leaks, keep an eye out for:

  • Puddles: Look for water around the base or beneath the tank.
  • Dampness: Check the floor or walls for damp spots.

How to Fix Low Flow Toilet Leaks

If you’re sure the leak is coming from the toilet, then you may need to replace or adjust your wax ring or tank bolts.

Tools Needed:

  • Wrench
  • Replacement wax ring or tank bolts
  • Sponge


  1. Turn Off the Water Supply: Stop the water flow by turning the shutoff valve.
  2. Dry the Area: Use a sponge to soak up any water around the leak.
  3. Replace the Wax Ring: If the leak is at the base, remove the toilet and replace the old wax ring with a new one.
  4. Tighten Tank Bolts: If the leak is from the tank, tighten the bolts or replace the rubber washers.

Need a Hand With Your Low Flow Toilet Problems? Get in Touch with Water Pros Plumbing

Low flow toilet maintenance is essential for ensuring it remains efficient and effective. If you’re not comfortable addressing issues like clogging, weak flushes, phantom flushing, refilling problems, and leaks, then we’d be happy to help you out here at Water Pros Plumbing.

Regular maintenance and timely repairs will not only save you money on utility bills, but also contribute to a more sustainable environment. So, don’t let your low flow toilet problems go for too long! Click here to schedule a Water Pros Plumber online, or call (480) 459-4424 today.

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