Building Inspection, Diagnosis & Repair Info

Photograph of huge water tanks at an old property with a well having a slow recovery rate. Home Water Quantity Requirements

How to estimate daily water quantity usage & wastewater quantity:

This article outlines typical daily residential water usage in gallons for people, appliances, and activities.

Page top photo: very large water storage tank inspected by the author [DF] suggested that this property was served by a wellwith a very poor flow rate.

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Home and Outdoor Living Water Requirements, Plumbing Fixture and Appliance Water Flow Rates

Household washing machine next to water heater with drip pan and behind a floor drain (C) Daniel Friedman at InspectApedia.comKnowing the average and peak water usage rates for people, fixtures, or buildings permits estimation of wastewater volume (for septic tank size determination) as well as water and well flow requirements and assists in water pump capacity or sizing specifications.

Flow rates for common household plumbing fixtures and appliances is given as well as estimates of peak demand water usage rates for residential buildings.

This data is also useful when evaluating adequacy of private well and water supply quantity, well flow rate, and wastewater loads on onsite residential septic systems.

Daily wastewater volume to be treated and disposed-of at a site determines the design parameters for onsite wastewater treatment or septic systems as well as suggesting choices among alternative septic designs and septic product

Photo above: in calculating the water usage for a building we consider the typical water usage variations by country and culture as well as the number of building occupants and the plumbing fixtures available.

How much water does a family use each day? What is the water flow rate for common household fixtures and appliances? How is this data used? Here we will review the following

The following table lists water usage requirements and typical fixture flow rates or device flow rates for home and outdoor living in the U.S.

Table 1. Home and Outdoor Living Water Requirements

Notes to Table Above

(a) water flow restricting valves and shower heads can reduce flow and water use by up to 50%.

Sources:

  1. RESIDENTIAL WATER USE TABLE [PDF], New York City Department of Environmental Protection, retrieved 2017/09/15, original source: http://www.nyc.gov/html/dep/html/residents/wateruse.shtml
  2. USDA "Water Systems Handbook." (Thanks to Keith Oberg, Professional Home Inspection Service, Binghamton, NY, for providing this information.)
  3. Clothes Washer Water Use, Home Water Works, Alliance for Water Efficiency, ret. 2017/09/16, original source http://www.home-water-works.org/indoor-use/clothes-washer

This data is used to estimate daily wastewater use in order to apply the septic tank sizing table located

at SEPTIC TANK SIZE

*Reverse Osmosis Systems - impact on septic systems and water use

What about water volume from reverse osmosis water treatment systems? These can vary by manufacturer with a range of 3:1 to 10:1 of waste to product efficiency. "Typically" for every gallon produced with a topo of the line system, 3 to 5 gallons goes into the septic tank. Less efficient systems (regardless of shutoffs) can dump up to 10 gallons to waste for every gallon that goes into the storage tank.

See REVERSE OSMOSIS CONCENTRATE WASTE DISPOSAL for further details. -- Larry Newcomb Encinitas Learning Center. We also discuss the effects of increased water usage when buildings use reverse osmosis (RO) for water purification.

Also see HOT WATER QUANTITY DAILY USE - daily hot water usage rates & tables

...

Other Water Usage- Requirements
Usage Type GPD Estimate
Apartments / Mobile home
Park		 See APARTMENT /
MOBILE HOME WATER USAGE
Beauty Parlor  200 per Operator/Station
Cooling Tower Tonnage x 4 (1)
Dormitory

40 gpm/person
-total

16 gpm/ person
-hot water
Factory 16 gpm/person
W/o process usage
Hospital

250 GPD/bed

170 GPD/hot water
Hotel

350 GPD/room

225 GPD/hot water
Motel See MOTEL WATEr

USAGE
Nursing Home

75 GPD/bed

50 GPD/hot water
Poultrty Processing 1 GPD/bird
Restaurant

10 GPD/person

4 GPD/hot water

+ 2 GPD for cocktail
lounge / bar
+ 30% If open 24-hrs
Schools See SCHOOL WATER
USAGE
  1. Cooling tower data assumes 2 gpm evaporation & 2 gpm bleed-off per ton of cooling capacity

Table 2: Peak Water Demand Usage Rates Translates into GPM Requirements for Water Pumps

Typical Residential Building Water Usage Rates: Flow Rates & Plumbing Fixtures
Water Usage Point Water Flow
GPM1		Peak
Demand2
Water Volume
Gals		Total Water Flow Rate GPM for Number of Bathrooms in Use at Once3
1 1 1/2 2 - 2 1/2 3 - 4 Comments
Bath Sink Lav
4
2
2
4
6
8
  
Dishwasher
2
14
    
3
3
  
Kitchen Sink
5
3
3
3
3
3
  
Shower
5
35
35
35
53
70
  
Toilet
4
5
5
10
15
20
  
Tub
5
35
35
35
53
70
  
Washing Machine
(Clothes)
5
35
  
18
18
18
 WASHING MACHINES & SEPTIC SYSTEMS
Peak Demand
Total Gallons2
  
45  
70  
98  
122  
 SEPTIC TANK SIZE
Minimum Water Pump
GPM Capacity Needed
  
7
10
14
17
 WATER PUMP CAPACITIES TYPES RATES GPM
Gallons Per Hour Flow Rate
  
420
600
840
1020
  

Notes to the Table Above

1. These are WSC's average fixture flow rates for common household plumbing fixtures. In some cases new fixtures are provided with low-flow-rate orifices or heads that can substantially reduce these flows. For example shower heads may restrict flow to about 2 gpm as may lavatory faucets.

2. Average household total gallons of water used during a theoretical peak demand period of seven minutes. I.e. all fixtures are in use overlapping in time for this interval.

This is the peak demand water volume used just during that interval. In my OPINION these numbers may not represent typical household usage.

For example someone washing dishes by hand at a kitchen sink usually runs water for longer than 3/5 of a minute (3 gallons taken at a 5 GPM rate means that the kitchen faucet was open for just about 36 seconds or that water was run more slowly so as to consume 3 gallons over a 7 minute interval).

3. Notice that there is a presumed reduction in flow rate when multiple bathrooms are in use simultaneously. For this reason the individual or single fixture flow rates are not simply added together. The table also assumes that either a shower or tub is in use in a given bathroom but not two such fixtures in the same bath for the same interval.

Adapted from: Water Systems Council (2003)

Large Scale Water Requirements

Watch out: the tables shown on this page are general guidelines only; your actual water use requirements may differ, and you may need to consult with a local engineer or other design professional.

Apartment / Trailer Park Water Usage
Number of
Units/Trailers		 Total GPD Peak
GPM
Flow 3		 Hot
Water

GPD		 Hot Water

Peak
Flow
4 720 22 240 12
5 900 25 300 15
6 1,000 30 360 20
8 1,440 40 480 26
10 1,800 50 600 30
15 2,700 75 900 45
20 3,600 90 1,200 55
30 5,400 110 1,800 65
40 7,200 135 2,400 75
50 9,000 140 3,000 85
100 18,000 220 6,000 110

Notes to the table above

  1. Assumptions: 3 people per living unit, 60 gpd/person
  2. Assuming also that a central laundry facility is provided for all occupancies
  3. Flush tank toilets, no landscape irrigation/sprinklers
  4. Source includes DWC cited in detail below

Motel Water Usage
Number of
Units		 Total GPD Peak
GPM

Flush-
Valves

Peak
GPM

Flush
Tanks

 Hot Water

GPD 3 		Hot
Water

Peak
GPM
10 1,000 65 26 400 17
20 2,000 90 43 800 25
30 3,000 109 55 1,200 36
40 4,000 128 65 1,600 43
50 5,000 145 75 2,000 48
75 7,500 180 105 3,000 62
100 10,000 210 130 4,000 73
125 12,50015,000 240 152 5,400 85
150   270 172 6,000 96

Notes to the table above

  1. Watch out: this table is for motels, NOT for hotels

    Ballpark water usage data for Hotels: 350 GPD per guest room (combined hot + cold water), or 170 GPD (hot water only) per bed.
  2. Sources: Op. Ct. table above, assumes 40 gallons total water use per day per person, and assumes 2 1/2 people per occupancy unit. Estimates do not include restaurants, bars, etc.
  3. 16 gallons per person
  4. From other GWD sources in the same document,

    With cafeteria and showers estimate 25 GPD per student (total water usage) or
    Estimate 10 GPD per student (hot water only).

    With cafeteria, no showers, estimate 15 GPD per student (total water usage) or

    Estimate 4 GPD per student (hot water only.

School Water Usage
Number of
Students		 Total GPD Peak
GPM

Flush-
Valves

Peak
GPM

Flush
Tanks

 Hot
Water

GPD 		Hot
Water

Peak
GPM
100 2,500 60 30 600 15
200 5,000 90 50 1,200 23
300 7,500 120 80 1,800 30
400 10,000 150 90 2,400 40
500 12,500 180 100 3,000 50
800 20,000 250 130 4,800 60
1000 25,000 300 160 6,000 70

Notes to the table above

  1. Sources: DWC Op. Ct. table above & cited in detail below, assumes 25 gallons of water usage per day per student

Water Requirements - Water Usage Levels - research & sources

  • DWC, WATER TREATMENT CATALOG [PDF] Duff Co. 201 E. Lafayette St. Norristown, PA 19401 USA, Tel: 610-275-4453 Web: https://www.duffcompany.com/departments/water-treatment/

    This 110-page document offers Duff's potpourri collection of water treatment information, including products that the company sells such as water filters and water treatment equipment. Included too are helpful tables of water requirements or water usage levels, some of which provided data that we excerpt below such as water use estimaets for schiools, apartments, motels, trailer parks. Duff does not give the original sources for that data.

...

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WATER QUANTITY USAGE TABLES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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Citations & References

In addition to any citations in the article above, a full list is available on request.

  • Thanks to Larry Newcomb Encinitas Learning Center, jayhawk@cts.com, for the above opinion concerning reverse osmosis treatment system water consumption rate
  • Water Systems Council, SIZING a WELL PUMP [PDF] (2003), Water Systems Council (WSC). WSC is a national nonprofit organization dedicated to promote the wider use of wells as modern and affordable safe drinking water systems and to protect ground water resources nationwide. Tel: 888-395-1033, Website: www.watersystemscouncil.org. Retrieved 1/20/2014,and de-novo 2026/05/20, local backup copy saved as Well-Pump-Sizing-WSC.pdf

    Excerpt: Proper sizing and selection of the components in your water well system, most notably the well pump, are essential to meet your water needs today and in the future.
  • Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP;
  • San Diego, CA, GRAY WATER SYSTEMS [Website] included older article: City eying home water-recycling technology; uses bath and washer water for irrigation., (ReWater Systems' equipment for greywater irrigation): This is an article from: San Diego Business Journal [HTML] (Digital) available online in digital format. I have not (yet) reviewed it -- DF>
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

    CONTINUE READING or RECOMMENDED ARTICLES.

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