Water Fixtures

  • toilets: 1.6 gallons per flush (gpf), generally termed "low-flow" toilets
  • kitchen faucets: 2.2 gallons per minute (gpm)
  • bathroom faucets: 2.2 gpm
  • showerheads: 2.5 gpm

  • toilets: 1.3 gpf
  • kitchen faucets: 2.0 gpm
  • bathroom faucets: 2.0 gpm
  • showerheads: 2.0 gpm

A wide array of high efficiency toilets (HETs) and dual-flush toilets that use 1.28 gpf or less are now available. Select models with high MaP scores. See the publication "High Efficiency Toilets Qualifying Products List" for a list of HET toilets and corresponding MaP scores. Low-flow aerators that can restrict and aerate flow to between 2.0 and 0.5 gpm are available for use with bathroom faucets. Aerating, low-flow showerheads that use 2.0 gpm or less are also available. The performance of many of these fixtures has improved over the original EPAct-compliant fixtures. When hot water is supplied with an on-demand (tankless) hot water heater, the flow rate from low-flow faucets, and even some low-flow showerheads, may not be enough to trigger the water heater. Care should be taken to ensure that the water heater's requirement for minimum water flow is met. In general, newer on-demand water heaters can sense lower hot water flow rates and work better with low-flow fixtures.

Options and Analysis

FAUCET
Flow rate 2.2 gpm 2.0 gpm 1.5 gpm 0.5 gpm
For water use only
Annual water use (gallons) 2,506 2,278 1,709 570
Annual water savings (gallons) - 228 797 1936
Annual water cost $17 $15 $11 $4
Lifetime water cost $165 $150 $113 $38
For electric water heating
Annual Energy Use (kWh) 121 110 83 28
Annual Energy Cost $13 $12 $9 $3
Lifetime energy cost $128 $117 $88 $29
Lifetime Energy and Water Cost $293 $267 $201 $67
For gas water heating
Annual Energy Use (therms) 4.1 3.8 2.8 0.9
Annual Energy Cost $5.40 $4.90 $3.70 $1.20
Lifetime energy cost $54 $49 $37 $12
Lifetime Energy and Water Cost $219 $199 $150 $50

TOILET
Flow rate 3.5 gpf 1.6 gpf 1.28 gpf
For water use only
Annual water use (gallons) 13,339 6,098 4,878
Annual water savings (gallons) (7,241) 0 1,220
Annual water cost $88 $40 $32
10 year water cost $880 $402 $322
10 year cost savings ($478) $0 $80

SHOWERHEAD
Flow rate 2.5 gpm 2.0 gpm 1.5 gpm
For water use only
Annual water use (gallons) 13,695 10,956 8,217
Annual water savings (gallons) 0 2,739 5,478
Annual water cost $90 $72 $54
Lifetime water cost $904 $723 $542
For electric water heating
Annual Energy Use (kWh) 1,510 1,208 906
Annual Energy Cost $160 $128 $96
Lifetime energy cost $1,601 $1,280 $1,502
Lifetime Energy and Water Cost $2,505 $2,003 $1,502
For gas water heating
Annual Energy Use (therms) 51.5 41.2 30.9
Annual Energy Cost $67 $56 $42
Lifetime energy cost $670 $562 $421
Lifetime Energy and Water Cost $1,574 $1,285 $963

All water calculations are based on $6.30/1000gallons water. Energy cost estimates based on $1.30 per therm and $0.106 per kWh. Lifetime for fixtures is 10 years. Consumer use rates from the U.S. Department of Energy.

Faucets - Water Use, Energy, and Cost
Low-flow faucets with aerators can wash hands effectively with as little as 0.5 gpm. These fixtures work well in bathrooms where the primary activity is washing. In the kitchen, faucets with flows less than 2 gallons per minute can make some kitchen activities more time consuming and labor intensive. However, some new kitchen faucets offer multiple "settings". The lever adjusts flows for hand washing up to 0.5 or 1.0 gpm. An extra push moves the lever into position for higher flows up to 2.2 gpm. By reducing the use of hot water, low-flow faucets accrue savings quickly from both water and energy costs. When replacing an older, non-EPAct compliant faucet, the cost of a new low-flow faucet will be recouped over the life of the fixture. One low-cost fix for existing, inefficient faucets is to install a low-flow aerator. The aerator screws into the nozzle of the faucet, making a faucet replacement unnecessary. The aerator adds air to the water stream and restricts flow to anywhere between 0.5 and 2.0 gpm. Aerators typically cost between $10 and $20.

Toilets - Water Use and Cost
Because toilets are replaced infrequently, even small reductions in water use can have major impacts over the lifetime of the toilet. Toilets installed prior to 1992 normally use 3.5 gallons per flush or more and should be replaced. Installation of a new high efficiency toilet (1.28 gpf) will reduce the fixture's water use by more than 60%. The cost of the new high efficiency toilet will be recouped in water cost savings.

Showerheads - Water Use, Energy, and Cost
Showerheads save water and energy by reducing the use of heated water. Cost savings are significant because savings accrue from both water and energy use reductions. The more use showerheads get, the faster water, energy, and cost savings add up. Showerheads are relatively inexpensive and many low-flow models can be purchased for between $10 and $20. The cost of a new low-flow showerhead should be recouped within 1 year. Over the life of the fixture, total cost savings can range up to $1000.

Practice
All the low-flow fixtures discussed here utilize standard installation practices and are straightforward to use. Typically, homeowners can install low-flow showerheads and faucet aerators themselves with minimal experience and tools.

Other Resources

Publications

Web Sites

1 "Why Water Efficiency?" WaterSense website. July 31, 2009. U.S. Environmental Protection Agency. Accessed July 2009. www.epa.gov/WaterSense/water/why.htm

2 "A Minnesota Groundwater Directory", MPCA website. September 2003. Minnesota Pollution Control Agency. Accessed September 2009. www.nextstep.state.mn.us/download/GroundWater_Directory.pdf

3 "Water Heating" U.S. DOE website. U.S. Department of Energy. Accessed September 2009. www.energy.gov/waterheating.htm