Stained toilet bowl indicates a running toilet (C) Daniel FriedmanSlow-Flushing Toilet Repair Guide
Diagnose & Repair Toilets

  • TOILET FLUSHES POORLY - CONTENTS: How to diagnose & fix a slow-flushing toilet - poor flush toilet repair guide. How to diagnose and fix a clogged toilet drain. How to fix a toilet that is overflowing when flushed - in an emergency. How to diagnose and correct drain noises occurring when the toilet flushes. Slow toilet tank fill problems. Toilets that keep running - fill valve does not shut off the toilet tank fill valve? Toilet flush valve or flapper valve problems. Toilet tank fill valves and water sanitation. Sewer gas odors in buildings traced to loose or leaky toilet drains. How to repair problems causing plumbing drain sounds
  • POST a QUESTION or READ FAQs about fixing slow-flushing toilets and johns or loos
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Slow flushing toilet repairs:

Here we explain how to diagnose and repair toilets that flush too slowly or have a weak flush, sometimes backing up.

We explain how to diagnose and repair problems with toilets, leaks, flushes, odors, noises, running and wasted water.

Our page top photo shows ugly staining in a toilet bowl - strong evidence that this toilet has been running, wasting water, possibly flooding the septic system, and sometimes giving bad flush performance as well. Details are below.

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Toilet Flushes Poorly - Too Slowly, or Leaves Waste in the Bowl

Toilet tank fill line (C) Daniel Friedman

There are several other reasons why a toilet fails to flush properly besides a clogged drain.

Here we list each cause of toilet flushing difficulties and suggest how to diagnose and repair the condition.

Poor-flushing low-water-consumption toilets: Keep in mind that modern low water consumption toilets (ASME/ANSI A112.19.M) are designed to use 1.6 gallons (6 liters) per flush or less - a desirable step in reducing water consumption in buildings.

But with the lower total flush volume designed into the toilet, if the toilet fill and flush valves are not properly adjusted, these toilets may cause complaints of poor performance. Don't rush to change out a toilet that is not working satisfactorily. toilet flush control tune-up may be all that's needed.

Our photo (above) shows the water level in a modern low-flush toilet tank, sitting just a fraction above the fill line. This toilet has adequate water to flush properly, if it is properly vented and if its drain is not blocked.

If the toilet is totally blocked and not flushing, see Toilet Drain Clogged.

At PLUMBING DRAIN VENTS we explain the basics of proper plumbing vent piping and how errors cause trap siphonage, odors, and noises.

More details about plumbing drain line venting can be found at PLUMBING VENT CODES & DEFINITIONS, also PLUMBING VENT DEFECTS & NOISES and at CLOGGED DRAIN DIAGNOSIS & REPAIR.

Also see WHAT CAN GO INTO TOILETS & DRAINS? both to avoid clogging drain lines and to avoid septic system damage if your building's wastewater is disposed-of on-site.

Toilet tank parts (C) DanieL Friedman

This sketch helps identify the toilet operating and repair parts we discuss in this article.

The Basics of How Toilets Work

While there have been improvements in toilet tank fill valves, flush valves, floats, and water savings, the design has remained about the same.

[Click to enlarge any image]

A flush lever moves an arm to lift a flapper valve or tank ball to permit water to rush into the toilet bowl below, washing away waste into the sewer pipe.

At the end of the flush cycle, a float arm, or a float moving on a vertical stalk (newer valves) drops to open a valve permitting the toilet tank to refill with water.

When the toilet tank water level reaches the proper level, the float closes the toilet tank fill valve.

Check for a Blocked Drain or Improper Venting

Low profile toilet (C) Daniel FriedmanIf the toilet always flushes, but it empties too slowly, or empties incompletely

Check & Adjust the Toilet Cistern or Tank Fill Volume

Toilet backupIf the toilet flushes poorly, leaving waste in the bowl and if you are sure that the drain is not blocked and that the vent works, check the toilet cistern volume and toilet bowl volume.

Toilet bowl fill tube disconnected Toilet bowl fill tube connected normally

See TOILET TYPES, CONTROLS, PARTS for a guide to identifying toilets by type, brand, parts & features.

At More Reading is a complete list of toilet trouble diagnosis and repair articles. Some toilet problems are fixed easily and right at the toilet by a simple adjustment, while others may not be the toilet's fault at all, and may need more thoughtful diagnosis and repair.

Lifting off the toilet tank top is often all you need to do to see how to fix a toilet flush problem.

Some of these simple toilet diagnosis steps require that you look into the toilet flush tank on the back of the toilet. Just lift the top off of the toilet tank and set it carefully aside on the floor where you won't break it or trip over it.

This article series TOILET REPAIR GUIDE discusses the cause, diagnosis, and repair of toilet problems (water closet problems) such as a toilet that does not flush well, clogged toilets, slow-filling toilets, running toilets, loose wobbly toilets, and odors at leaky toilets.


Continue reading at TOILET CLOGGED to diagnose and fix a blocked or clogged toilet or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.



Or see these

Toilet Repair Articles

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