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Home Technical Data Domestic Water Design Data
Domestic Water Design Data
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Tables 1 to 3 provide typical water usage for various appliances
(e.g. showers,
taps and WCs) and for various building types. Table 4 provides
typical
allocation of sanitary facilities (i.e. toilets / wash basins)
for a given building size.
Table 5 suggests suitable domestic water header sizes for a
given number of
appliances. It should be noted that as each project is
different, these tables can
provide general guidance only.
Table 1: Total Domestic Water Demand for Various Applicance
Types
Total Water Flowrate Total Water Demand
Cisterns (WC's) Refill 0.1 litres per second 4 to 5 litres per
flush
Hand Basin Tap 0.15 litres per second 5 litres per use
Hand Basin Tap (Spray
type)0.1 litres per second 3 litres per use
Bath0.3 to 0.6 litres per
second60 to 100 litres per use
Urinals 0.1 litres per second 4 litres per flush
Shower (Domestic) 0.15 litres per second40 to 90 litres per
showerSafety Shower (Deluge
Type)0.4 litres per second
100 to 250 litres per
use
Sink0.2 to 0.3 litres per
second10 to 18 litres per use.
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Where applicable, the above figures include for both hot and
cold water
Table 2: Typical Domestic Water Usage in
Different Building Types
Domestic Household (Single Occupant) 200 litres per day
Domestic Household (2 Occupants) 150 litres per day per
person
Domestic Household (3 or more Occupants 100 litres per day per
personHotels 150 litres per day per person
Offices (without canteen facilities) 40 litres per day per
person
Offices (with canteen facilities) 45 litres per day per
person
Other Public Buildings (e.g. cinemas, bars) 3-10 litres per day
per person
These figures are for the supply of water for toilets, wash
basins, sinks, showers
and drinking fountains etc. They make no allowance for water
demand from
industrial users, such as industrial cleaning, cooling,
firefighting.
Table 3: Typical Domestic Hot Water Usage in Different Building
Types
Household (Single Occupant) 100 litres per day
Domestic Household (2 Occupants) 75 litres per day per
person
Domestic Household (3 or more Occupants 50 litres per day per
person
Hotels 100 litres per day per person
Offices (without canteen facilities) 10 litres per day per
person
Offices (with canteen facilities) 15 litres per day per
person
Other Public Buildings (e.g. cinemas, bars) 1-2 litres per day
per person
Need to design a domestic water
system? See our domestic water
design guide
Domestic Water Design Guide
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These figures are based on the supply of water for toilets, wash
basins, sinks,
and showers etc. They make no allowance for water demand from
industrial
users, such as industrial cleaning.
Table 4: Typical Allocation of Sanitary devices for Commercial
Buildings
Toilets (WC's)
1 + 1 per 25 men
1 + 1 per 14 women
Urinals 1 + 1 per 25 men
Wash Basins1 + 1 per 25 men
1 + 1 per 14 women
For many commercial buildings, requirement for showers are
minimal. However,
at some industrial facilities, showering at the end of shift is
commonplace.
Typically allow 1 shower facility per every 5 shift workers.
These figures are acceptable for buildings with up to 100
persons. For larger
buildings, allocation of sanitary devices per person can be
reduced slightly.
Table 5: Suggested Maximum Number of Applications for a given
Water Header
Size
Water appliances (e.g. showers, taps, WC cisterns) are used at
irregular intervals
and often for short periods of time. Consequently, it is not
usually not sensible to
size the header based on all the appliances operating
simultaneously. Takingthis into account, the following table gives
suggested maximum number of water
appliances (e.g. showers, taps, WC cisterns) that can be fed off
a given domestic
water header size.
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During detailed design, the domestic water system hydraulics
should be
calculated. This is especially important for systems with either
long pipe runs or
heavy peak demands.
Suggested Water Header Size
1 Appliances 15 mm NB (1/2 inch)
2 to 4 Appliances 20 mm NB (3/4 inch)
5 to 8 Appliances 25 mm NB (1 inch)
9 to 50 Appliances 40 mm NB (1 1/2 inch)
55 to 99 Appliances 50 mm NB (2 inch)
100 to 200 Appliances 65 mm NB (2 1/2 inch)
