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PLUMBING SYSTEM INSPECT DIAGNOSE REPAIR
AGE of PLUMBING MATERIALS & FIXTURES
AIR DISCHARGE at FAUCETS, FIXTURES
ANTI SCALD VALVES
ANODES & DIP TUBES on WATER HEATERS
BACKUP PREVENTION, SEPTIC
BACKUP PREVENTION, SEWER LINE
BACKWATER VALVES, SEWER LINE
BATH & KITCHEN DESIGN GUIDE
CHEMICAL CONTAMINANTS in WATER
CHEMICAL ODOR SOURCES
CHLORINE IN DRINKING WATER
DEBRIS in WATER SUPPLY, Water Heater
DEPTH of SEPTIC TANK
DRAIN & SEWER PIPING
FAUCETS & CONTROLS, KITCHEN & BATH
FAUCETS, OUTDOOR HOSE BIBBS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOR DRAIN / TRAP ODORS
FLUSHOMETER VALVES for TOILETS URINALS
GAS PIPING, VALVES, CONTROLS
GALVANIC SCALE & METAL CORROSION
HARD WATER - SOFTENERS
HEAT TAPES, Heat, Insulation prevent Freeze-Up
LEAD POISONING HAZARDS GUIDE
LEAD IN DRINKING WATER, HOW to REDUCE
METHANE GAS SOURCES
MIXING / ANTI-SCALD VALVES
MUNICIPAL WATER PRESSURE IMPROVEMENTS
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER
ODORS, SEPTIC or SEWER
ODORS SEWER GAS in COLD WEATHER
ODORS, SULPHUR SMELL SOURCES
ANIMAL or URINE ODOR SOURCE DETECTION
PIPING IN BUILDINGS, Clogs Leaks Types
PLUMBING FIXTURES, KITCHEN, BATH
PLUMBING NOISE TRANSMISSION CONTROL
PLUMBING VENT DEFINITIONS & CODES
PLUMBING VENT DEFECTS & NOISES
PUMPS, WATER REPAIR
RELIEF VALVE LEAKS
RELIEF VALVE, TP VALVE, BOILER
RELIEF VALVE, TP VALVE, STEAM BOILER
RELIEF VALVE, WATER HEATER
RELIEF VALVE, WATER TANK
REPAIR BURST LEAKY PIPES
METHANE GAS HAZARDS
SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SHUTOFF VALVE LOCATION, USE
SULPHUR & SEWER GAS SMELL SOURCES
SWEATING (CONDENSATION) on PIPES, TANKS
TOILETS, INSPECT, INSTALL, REPAIR
WATER, WELLS, WATER TANKS: TESTING GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMPS & TANKS
WATER SOFTENERS & CONDITIONERS
WATER SOURCE ALTERNATIVES
WATER SUPPLY & DRAIN PIPING
WATER SHUTOFF VALVE LOCATION, USE
WATER SHUTOFF VALVE, WELL PUMP
WATER TESTS, CONTAMINANTS, TREATMENT
WELLS CISTERNS & SPRINGS
WINTERIZE A BUILDING
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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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 DEFINITIONS & CODES, als PLUMBING VENT DEFECTS & NOISES and at CLOGGED DRAIN DIAGNOSIS & REPAIR. Also see WHAT CAN GO INTO TOILETS & DRAINS?.
The sketch (left) 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
Check & Adjust the Toilet Cistern or Tank Fill Volume
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 the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
(Mar 1, 2014) Anonymous said:
Thanks for taking the time to post your note, Anon; don't hesitate to ask if you can't find information you need, as that question helps us both. Daniel
Question: dishwashing detergent & increasing the cistern water level helped clear up a slow flushing toilet
(Sept 11, 2014) Anonymous said:
Thanks for the feedback Anon, it will assist other readers.
Question: bad smell out of drains when toilet is flushed
(Oct 15, 2014) Lisa said:
(Oct 16, 2014) lyndamae ooms said:
i am wondering why this is happening? we never had a problem before..
also my house sunk about 1 and a half inches and it was raised again this summer... could something be broken inside all the plumbing inside the house or outside the house... the sewer pipe under the house going into the septic tank was severed from the house side.... and replaced with ABS sewer pipe to bring it up to code... it was about four inches from the house and four inches from the tank that was replaced. help i just don't know what to do.
(Jan 2, 2015) Anonymous said:
Anon noises or odors at nearby plumbing drains when a toilet is flushed often means that the plumbing vent system is blocked or incomplete.
Question: toilet flushes better when pour a bucket of hot tap water into it
(Jan 3, 2015) Anonymous said:
Probably the volume of flush water and the speed of its delivery into the toilet bowl is what makes the difference. I've seen this problem in some older homes that used an under-sized drain line or in drains that were partly blocked by corrosion or deposits. Check that the plumbing vent system is functional while you're debugging this issue.
Question: toilet flushes then sewage returns back into the bowl
(Jan 5, 2015) Peter said:
You might see this if we have a pair of toilet troubles:
With this pair of problems a flush can send a bolus of water and waste down the drain, compressing air in the drain piping; but as the compressed air and sewage meet a blockage the air pressure sends the waste back to the toilet.
How quickly does the waste return. If it's almost immediately I suspect that there is a blockage close to the toilet. If it recurs later I suspect there is a blockage more distant down the sewer piping or in a private septic system - if your building is connected to one.
Is this problem unique to just one toilet in the building?
Don't forget to check other causes of a slow-flushing toilet, especially a clogged siphon jet (in the bottom, front of low flow toilets) or an obstruction in the vent pipe up on the roof. The four main causes of a slow flush are (Actually David listed five causes of slow toilet flush)
Not enough water in the toilet tank or cistern (not really - this doesn't cause a *slow* flush as much as an incomplete one - Ed)
Partly clogged drain (yes we discuss this above - ed)
Clogged rim holes around the toilet bowl (same effect as not enough water in the tank or cistern but you should indeed check for this - Ed.)
Clogged "siphon jet" (check in the toilet tank or cistern: if the small tube that sends water to the toilet bowl is not properly connected (sending water into the cistern or toilet tank instead) then the effect will show up as not enough water in the toilet bowl at the end of the tank or cistern fill cycle - Ed)
Clogged "air vent" (properly, this is a blocked, clogged, or missing plumbing vent, discussed in this article series - Ed.)
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