How to estimate daily water quantity usage & wastewater quantity:
This article outlines typical daily residential water usage in gallons for people, appliances, and activities. s.
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Knowing 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
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 | ||||
Use | Flow Rate US Gallons GPM |
Flow Rate Liters LPM |
Total Use U.S. Gals. |
Total Use Liters |
Adult or child total water use | - | - | 60 - 70 / day1 50 - 100 / day2 |
227 - 2651 189 - 3792 |
Baby care | - | - | 100 / day | 379 |
Bathroom % of Residential Water Use | 50 - 75%1 | |||
Bathroom lavatory sink | 2 | 7.6 | 1 - 2 / use | 3.8 - 7.6 |
Backwash filters | 10 | 37.9 | 100-200 / backwash cycle | 379 - 757 |
Dishwasher | 2 | 7.6 | 5 - 5 / load | 19 - 57 / load |
Garbage Disposer | 3 | 11.3 | 4 - 6 / day | 15 - 23 / day |
Kitchen sink (a) | 3 | 11.3 | 2 - 4 / use | 7.6 - 15 / use |
REVERSE OSMOSIS water treatment |
* | 3 - 10 wastewater
/ gal. of treated water produced |
11.3 - 37.8 / gal | |
Shower or tub | 5 | 19 | 25 - 60 / use | 95 - 227 / use |
Shower head, standard | 4 - 7 | 15 - 26.5 | ||
Shower head, low-flow | 2 or less | |||
Toilet flush - standard pre 1980 toilets | 3 | 11.3 | 4 - 7 / use | 15 - 26.5 / use |
Toilet flush - vintage 1980-1992 | 3.5 / use | 13 / use | ||
Toilet flush - low-water-consumption | 1.6 / use or less | 5.7 / use | ||
Toilet flush - high-efficiency HET | 1.28 / use | 4.84 / use | ||
Outside hose faucet | 5 | 19 | depends on run time | |
Water softener regeneration | 5 | 19 | 50 / 100/cycle | 189 / 379 |
Washing machine, clothes, standard domestic |
5 | 19 | 29-55 / load2, 3 |
109 - 208 / load |
Washing machine, clothes, water-efficient |
15-30 / load2, 3 9.5 / cu. ft. capacity |
57 - 114 / load | ||
Washing machine, clothes, high efficiency |
5 / cu.ft. capacity |
19 / cu.ft. capacity |
(a) water flow restricting valves and shower heads can reduce flow and water use by up to 50%.
Sources:
This data is used to estimate daily wastewater use in order to apply the septic tank sizing table located
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 16 gpm/ person |
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 |
Schools | See SCHOOL WATER USAGE |
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 |
|||||||
Dishwasher |
|||||||
Kitchen Sink |
|||||||
Shower |
|||||||
Toilet |
|||||||
Tub |
|||||||
Washing Machine (Clothes) |
WASHING MACHINES & SEPTIC SYSTEMS | ||||||
Peak Demand Total Gallons2 |
SEPTIC TANK SIZE | ||||||
Minimum Water Pump GPM Capacity Needed |
WATER PUMP CAPACITIES TYPES RATES GPM | ||||||
Gallons Per Hour Flow Rate |
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)
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 |
Motel Water Usage |
|||||
Number of Units |
Total GPD | Peak GPM Flush- Valves |
Peak Flush |
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 |
School Water Usage |
|||||
Number of Students |
Total GPD | Peak GPM Flush- Valves |
Peak Flush |
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 |
...
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