Toilet Inspections

by Nick Gromicko, CMI® and Kenton Shepard 
Toilets are complicated fixtures that may fail in numerous ways. This article describes typical toilet defects, provides information for diagnosing such defects, and offers an overview of toilet designs and functionality. Standard gravity toilet  
InterNACHI Toilet Trivia:
  • “Sitting toilets,” while popular in Western countries, are not as common as “squat toilets” found in most of the world.
  • The film “Psycho” (1960) was the first American movie to show a flushing toilet. The scene, believed by many to be indecent, lead to an outburst of complaints.
  • An average person visits the toilet 2,500 times a year, about six to eight times a day. You will spend about three years of your life on the toilet.
  • Most pharmaceuticals are excreted through urination, which enters sewer systems and eventually contaminates fish. A recent study by the EPA has found fish containing trace amounts of cholesterol-lowering drugs, estrogen, antibiotics, caffeine and anti-depressants.

How does a toilet work?

When a standard residential toilet, called a gravity toilet, is ready for use, both tank and bowl contain water. When the lever is pressed, it lifts a rubber stopper, called a flapper, which lets the water in the tank flow into the bowl. The water enters the bowl through small holes around the inner bowl top and at the siphoned jet hole at the base of the bowl. Gravity forces the bowl's water and waste down the waste pipe. The water flowing into the bowl also cleans the bowl. The bowl's water is replenished by water entering from the tank through a refill tube.


Inspectors should check for the following defects and perform the following tests:

  • cracks. Cracks anywhere on the toilet tank or bowl (as well as on any other fixtures) should be written up as defects.
  • flush all toilets in the home. Unlike windows, of which the inspector is only required to test a representative number, every toilet should be tested. Specifically, inspectors should ask themselves the following questions while operating toilets:
    • Does the toilet run continuously? Toilets that run continuously will waste large amounts of water. If the house receives public water, wasted water will lead to an increased water bill. If the house is on a well, however, a continuously running toilet can be very damaging; continuously running toilets can cause the well to run dry and the pump to burn out, and inspectors should warn their clients of this danger.
    • Does the toilet take too long to flush?
    • Does the toilet take too long to fill?    
  • the size of the water tank. According to a federal law passed in 1994, new toilets are not allowed to use more than 1.6 gallons per flush (GPF). Toilets manufactured prior to 1994 are not subject to this law. GPF is normally printed on one of the following locations:
    • on the bowl;
    • stamped on the underside of the tank lid; or
    • on the inside of the tank.
  • the connection between the bowl and the tank. While straddling the bowl, the inspector can check to see if this connection is sturdy. Leaks may result from a weak connection.
  • the firmness of the connection between the toilet bowl and the floor. Inspectors can test this connection by straddling the bowl and trying to gently rock it from side to side. A loose bowl can leak into the floor and cause wood decay in wood floors. Inspectors should recommend that bowls that are not firmly attached to the floor be refastened.
  • Test for leaks.
    • A dye pill can be dropped into the water tank to see if the dye makes its way into the bowl, without operating the toilet. Inspectors can wait approximately 15 minutes after placing the dye pill in the tank to see if it has leeched into the bowl. These pills are inexpensive and may be obtained for free from the local water utility.
    •  A moisture meter is a useful tool for examining whether water has leaked from the toilet into the surrounding floor.

Note: Inspectors should never operate the water shut-off valve behind the toilet, or any other water shut-off valve.

Alternative Toilet Designs

  • Dual-flush toilets, also known as duosets, offer the user a choice of flushes. Two buttons allow for the user to select between a flush for solid or liquid waste, or 1.6 gallons and 1 gallon, respectively. Since most households' flushes are for urine, dual flush toilets can save a significant amount of water, roughly 30%. This interactive toilet design helps conserve water and has caught on quickly in countries where water is in short supply, such as Australia, where the dual flush toilet was invented in 1980.
  • Unlike a septic system, which uses anaerobic (without oxygen) bacteria to break down sewage and waste, composting toilets use aerobic (oxygen-using) bacteria and fungi, which do not require that the waste be covered with liquid. Properly configured and used, a composting toilet reduces waste to between 10% to 30% of its original volume. The resulting product, called humus, is stable and resembles soil. In many areas of the world, humus is added to soil used for food cultivation, but the U.S. prohibits this practice and requires that humus be disposed of as specified by the local Authority Having Jurisdiction (AHJ). Composting toilets use little or no water, require no expensive sewage systems, have little environmental impact, and produce a valuable resource for gardening.Pressure assist toilet
  • Vacuum-assist toilets, which were first manufactured by Fluidmaster give a complete, clean flush using only the rim holes inside the upper toilet bowl, and lack a siphon jet hole at their base. When flushed, water flowing out of the tank creates suction in the vacuum tank and trap-way to help suck the waste out of the bowl.
  • Pressure-assist toilets:  This toilet's water supply provides the pressure to compress air within a sealed plastic reservoir inside the tank. When the incoming water reaches the fill line, the tank is pressurized and ready for the next flush. Although pressure-assist toilets are somewhat noisy during flushing as pressure is released, up to 80% of the flush water is used to purge the bowl, making for a very efficient flush. These toilets work well as long as the household water pressure is at least 25 pounds per square inch. Pressure-assist toilets can solve problems in homes with older plumbing systems where gravity-fed 1.6-gpf toilets just aren't strong enough to pull waste through the older pipes. Pressure-assist toilets are generally better than typical gravity toilets, but the more complicated mechanism makes them more expensive to buy and repair.

In summary, toilet defects include, but are not limited to:  water leakage, cosmetic blemishes, and inability to expel contents.