Household Leak Detection and Mitigation Introduction

Leaks from pipes, plumbing fixtures and fittings are a significant source of water waste for water utilities and the residential customer.  Research has shown that the typical home loses 2,000 to 20,000 gallons (7.6 m3 to 76 m3) of water per year due to leaks.  Some leaks are readily apparent, such as dripping faucets and leaking water heaters.  Unfortunately, many leaks go undetected for years because the source of the leak is not visible.  When leaks are hidden, the water escapes undetected, such as toilet flapper valves and cracked water supply lines.  Individually or collectively, the leaks in a single home can easily waste thousands of gallons of water each year; costing money to BOTH the water customer and the utility.

The true cost of leaks has been somewhat misrepresented in the past.  Most water conservation literature informs customers the value of fixing the leak can be calculated by multiplying the water volume of the leak -times the per-unit cost of the water, as charged by the water utility.   In fact, many water meters do not register water usage unless the leak exceeds one pint per minute, or 360 gallons (1.3 m3) per day.  This allows more than 100,000 gallons (378.4 m3) per year to slowly pass through the meter without garnering revenue for the water utility.   More information regarding the ability of meters to detect leaks can be found at:

There in no one easy method to detect leaks.   A comprehensive approach must be used to detect leaks from all of the household’s appliances, fixtures, or fittings.  The following is an overview of different methods that can be employed.

Whole House Meter Check

Larger leaks or a combination of small leaks can often be detected by the water meter.   A whole house meter check can sometimes inform you of a leak and its flow rate, but does not usually indicate where the leak is occurring.  Performing this leak check includes the following procedures:

1. All water is turned off inside and outside the home.  Special notice must be given to occupants to not use any water (including toilet flushing) for the next 20 minutes.  This test must be performed when no automatic water equipment is used, such as irrigation controllers, clothes washers, dishwashers, etc.   Occupants should also avoid using ice from refrigerator ice and water dispensers.

2. Record the reading of the water meter, and wait 15 minutes.  Be certain no one uses any water during this time.

3. Record the reading of the meter again.  If the meter has recorded water use during the test, it might be due to a leak.  Verify that the water use is not due small appliances such as water filters, water softeners, or whole house humidifiers.  Perform test again, if necessary,

4. You can calculate monthly water waste from leaks by multiplying the water usage in the “15 minute” test period times 2,880.   Remember to verify the units measured by the meter; some meters record usage in gallons, and some record usage in cubic feet. (There are 7.48 gallons per cubic foot)

Meter sensitivity varies greatly among meter makes and models.  Even the age of the meter will affect its ability to detect small leaks in the home; meters become less sensitive as they age.   The meter test only verifies large leaks; it cannot assure small leaks do not exist within the home.   Even when leaks are detected, this test does not indicate the location of the leaks.    Further investigation is needed to detect and locate all significant leaks.

Water Supply Line

There are sometimes leaks between the meter and the home, in the water supply line.  These leaks are often times difficult to detect because the supply pipe is usually buried at least 3 feet (.91 m)below the ground surface.  Sometimes the leaking water will travel along the pipe, back to the meter.  If the meter box contains water, and the water is not due to rain or irrigation run-off, this may indicate a leak in the supply line.  Another common exit point for the leaking water might be where the supply line rises above the ground and/or enters the house.   If the soil is constantly damp at these locations, not due to rain or irrigation, this might indicate a leak.   In cases of severe leaks, the water will seep up towards the ground surface, usually directly above the path of the underground pipe.  Most often, leaks between the meter and the house are the responsibility of the homeowner; leaks from the meter or pipes leading from the main to the meter are the responsibility of the water utility.  The water utility should be contacted before any attempt to repair the water supply pipe.

Breaks in the water supply line require the services of a trained professional.  If the utility deems the leak to be the responsibility of the homeowner, a professional plumber should perform all repair work.  This repair should never be attempted by a homeowner.   It is important to repair supply line leaks quickly, as the leaks tend to be very large and can cause structural damage to the home.

Faucets, Showers and Tubs

Faucet leaks are a common occurrence and usually simple to repair.  That slow dripping faucet is not just an annoyance; it wastes surprising amounts of water.  A faucet dripping slowly at only one drop every two seconds will waste more than 1,000 gallons (3.7 m3) per year.   To estimate the volume of water wasted per year, simply count the number of drips per minute.  Every drip recorded in the one minute time span equates to 35 gallons (132.5 L) per year.  A faucet dripping 45 drops per minute is leaking 1,575 gallons (5.96 m3) annually (45 drops x 35 = 1,575).

The repairs necessary to stop the leaks depends on the type of faucet, and there are four basic types found in most homes:  compression valve, ball types (sometimes called delta), cartridge types, and ceramic discs.  Each type of faucet is has unique methods of repair.  It is no longer accurate to encourage homeowners to replace the washers; many types of faucets require new o-rings, cartridges, or ceramic discs.  With some instruction and guidance, most repairs can be accomplished by homeowners accustomed to using tools and making minor home repairs. 

When inspecting the home for faucet leaks, it is important to inspect other water valves around the home, including:  showers, bathtubs, water heaters, hose bibs, laundry basins, utility sinks, etc.  


Toilets are one the most common sources of leaks in the home, usually unnoticed by the residents because the leaks are often silent and out of view.  Most toilet leaks will send the wasted water directly into the sewer line without detection by residents.  Several research studies have found 20% to 35% of all residential toilets leak to some degree. 

Large toilet leaks can be detected when the valve constantly emits a hissing or gurgling sound when the toilet is not in use.  Smaller, though significant, leaks require the further investigation.   Removing the tank lid to inspect the flush mechanisms is the first step.    

The water level in the tank should be no higher than 1 inch below the top of the overflow tube.  Some tanks require a lower water level, but none are ever higher.  If the water level is to the very top of the overflow tube, water is slowly leaking into the overflow tube and down the drain.  The problem has one of three causes:  1) the water level is adjusted too high; 2) the float is damaged and not shutting off the refill valve; or, 3) the refill valve (ball-cock assembly) is worn and needs replacement.


Performing a dye test will allow detection of leaks in the flapper valve.  Test procedures include placing dye tablets into the tank water to turn the water dark blue.   If the dark blue water appears in the bowl within 15 minutes, there is a leak in the flapper valve.     

There are several causes for these leaks, but flapper valves are the most common problem. The flapper provides the barrier, holding the water in the tank until the user activates the flush handle, pulling on the chain attached to the flapper valve.  When the flapper is raised, the water in the tank rushes into the bowl creating the flush.  After the flush is complete, the flapper falls back down onto the valve seat to retain the water as the tank refills.  Leaks occur when the flapper valve does not create a water tight seal.  The seal can be compromised due to several reasons:  a) the chain snagging, not allowing the flapper to drop completely onto the valve seat; c) the valve seat is worn; or c) the flapper is worn or warped.  A worn flapper is the most common cause by far, and can be easily replaced.

Whole House Humidifiers      

Some homes have whole house humidifiers, most common in homes with forced-air central heating systems.  This humidifier is usually attached to the furnace plenum and directly plumbed to the water supply pipes to provide constant water supply to the appliance’s water reservoir.  The equipment often includes an overflow drain to the sewer in case the refill valve fails to close.   When the valve does fail, the water is sent directly into the sewer.  This allows leaks to occur for months or years before anyone realizes the water waste.   It is important to check the operation of this equipment regularly during the heating season, and turn off the water supply to the equipment during seasons of non-use.

Evaporative Coolers

In arid climates, some homes are cooled by evaporative coolers, sometimes called swamp coolers or desert coolers.  The devices use the evaporation of water to cool air sent into the home.  More detailed information can be found at:      The evaporative coolers are most often connected to the home water supply to maintain water in the cooler’s reservoir.  The refill valve for the reservoir occasionally fails to close, causing a constant stream of water to enter the reservoir and drain out the overflow line.  The overflow line is often connected to wastewater drain, allowing the leak to persist for months or years before the water waste is detected.   The cooler can be easily checked for leaks by shutting off the equipment, and observing any water draining through the overflow line.  Leaking coolers can usually be repaired by simply replacing the refill valve, re-circulation pump, or water lines.