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A toilet flush can use about 1.28 to 6 gallons of water, depending on the age and type of toilet. Most newer toilets use 1.6 gallons per flush or less.
EPA WaterSense-labeled toilets use 1.28 gallons per flush or less. That is 20% less than the current U.S. federal standard of 1.6 gallons per flush. Older toilets can use much more water.
How Much Water Does One Toilet Flush Use?
Here are common flush volumes:
| Toilet type or age | Water per flush |
|---|---|
| WaterSense toilet | 1.28 gallons or less |
| Standard newer toilet | About 1.6 gallons |
| Toilet from about 1980–1994 | About 3.5 gallons |
| Toilet from before 1980 | About 5 gallons |
| Some very old toilets | Up to 6 gallons |
EPA uses about 5 gallons per flush as an estimate for toilets installed before 1980, 3.5 gallons for toilets installed from 1980 through 1994, and 1.6 gallons for toilets installed after 1994.
Some older toilets can use as much as 6 gallons with every flush.
In liters, the common amounts are roughly:
- 1.28 gallons = 4.8 liters
- 1.6 gallons = 6.1 liters
- 3.5 gallons = 13.2 liters
- 5 gallons = 18.9 liters
- 6 gallons = 22.7 liters
How Much Water Does a Toilet Use Per Day?
A useful planning estimate is about 5 flushes per person per day. EPA uses 5 flushes per person per day in some residential water-use calculations.
Using that estimate:
| Water per flush | Per person per day | Per person per 30 days |
|---|---|---|
| 1.28 gallons | 6.4 gallons | 192 gallons |
| 1.6 gallons | 8 gallons | 240 gallons |
| 3.5 gallons | 17.5 gallons | 525 gallons |
| 5 gallons | 25 gallons | 750 gallons |
| 6 gallons | 30 gallons | 900 gallons |
Your actual use may be higher or lower. It depends on how many people are home during the day and how often each toilet is used.
How Much Water Does a Family of Four Use for Toilet Flushing?
For four people flushing about five times each per day, the household would have about 20 flushes per day.
That gives these rough totals:
| Toilet flush volume | Daily use | 30-day use |
|---|---|---|
| 1.28 gallons | 25.6 gallons | 768 gallons |
| 1.6 gallons | 32 gallons | 960 gallons |
| 3.5 gallons | 70 gallons | 2,100 gallons |
| 5 gallons | 100 gallons | 3,000 gallons |
| 6 gallons | 120 gallons | 3,600 gallons |
This is why the toilet can be an important part of a household water budget. EPA estimates that toilets account for nearly 30% of an average home's indoor water use.
How to Find Your Toilet's Flush Volume
Do not assume the toilet uses a certain amount based only on its appearance.
Look for a marking on the toilet. You may see it:
- Behind the seat
- Near the bowl or tank
- Inside the tank
- On a manufacturer's label
Look for GPF, which means gallons per flush. A marking such as "1.28 GPF" means the toilet is designed to use about 1.28 gallons for each flush.
You may also see LPF, or liters per flush.
If you cannot find a marking, the toilet's model number may help identify its rated flush volume.
Dual-Flush Toilets Use Different Amounts
A dual-flush toilet normally has a reduced flush and a full flush.
The reduced flush is meant for liquid waste. The full flush uses more water for solid waste.
Because there are different designs, do not assume that every dual-flush toilet uses the same amount. Check the toilet's label or specifications.
For WaterSense-labeled toilets, EPA sets water-efficiency and flushing-performance requirements rather than treating low water use alone as enough for certification.
A Running Toilet Can Use Much More Water
The rated gallons per flush only tells you what should happen during a normal flush.
Understanding common sources of household water leaks helps compare installation planning for dependable ongoing service.
A leaking toilet can continue sending water into the bowl between flushes. Common causes include:
- A worn or poorly seated flapper
- A fill valve that does not shut off correctly
- Water set too high in the tank
- A problem with the flush valve
If you hear the toilet refill when nobody has used it, check for a leak.
Fixing a leak may reduce water use more than changing normal flushing habits.
Estimating Toilet Water Needs for a Rainwater System
Toilet flushing is a non-potable use. Non-potable means the water is not intended for drinking.
If you are estimating how much stored rainwater you would need for toilet flushing, use:
Daily toilet water = people × flushes per person × gallons per flush
For example, suppose four people use a 1.28-gallon toilet and average five flushes each per day:
4 × 5 × 1.28 = 25.6 gallons per day
For 30 days:
25.6 × 30 = 768 gallons
That does not mean you need exactly a 768-gallon tank. Rainwater system sizing also depends on:
- Roof collection area
- Local rainfall
- Storage capacity
- Water used for other purposes
- Overflow and collection losses
- Dry periods between storms
A rainwater supply connected to household toilets also needs more than a tank and a hose. Plumbing must keep non-potable water separate from drinking-water piping. Pumps, backflow protection, treatment or screening, controls, and local plumbing requirements may also apply.
Check with your local plumbing or building authority before connecting collected rainwater to indoor fixtures.
Frequently Asked Questions
How many gallons does a modern toilet use per flush?
A typical newer U.S. toilet uses about 1.6 gallons per flush or less. WaterSense-labeled toilets use 1.28 gallons per flush or less.
How much water does an old toilet use per flush?
Older toilets vary widely. EPA uses about 3.5 gallons per flush for toilets installed from 1980 through 1994 and about 5 gallons for toilets installed before 1980. Some older toilets can use as much as 6 gallons.
How many times does one person flush a toilet per day?
About five flushes per person per day is a reasonable planning estimate. EPA uses five flushes per person per day in residential water-use calculations.
How much toilet water does one person use per month?
At five flushes per day, a 1.28-gallon toilet would use about 192 gallons per person over 30 days. A 1.6-gallon toilet would use about 240 gallons.
How much toilet water does a family of four use per month?
With five flushes per person per day, four people would use about 768 gallons per month with 1.28-gallon toilets or about 960 gallons with 1.6-gallon toilets.
What does GPF mean on a toilet?
GPF means gallons per flush. It tells you the rated amount of water the toilet uses during a normal flush.
Can rainwater be used for flushing toilets?
Rainwater can be used for toilet flushing in some locations, but indoor rainwater systems must be designed to prevent cross-connections with drinking water. Plumbing, backflow protection, treatment, labeling, and permit rules vary by location. Check current local requirements before connecting a rainwater system to indoor toilets.
