Page 17 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 17
8 Griha Manual: Volume 4
Water eficient ixtures
Water closets (WCs)
Water closets or toilets can use water anywhere between 13.5–9 litres per flush for the conventional
single flush models. Low flush toilets use on an average 4–5 litres for 6/3 dual flush toilet or even
lesser for the new versions of dual flush model – 4.5/3.
There are three basic types of WCs
1. Gravity tank WC
This comprises of a bowl or pan with a tank connected by a flush pipe. Older versions of this
system use up to 13.5 litres of water for every flush, whereas the latest ones use 4.5 litres for
a full flush.
2. Flush valve operated
This type of toilet uses a flushometer valve directly connected to the water supply plumbing.
This valve controls the quantity of water released over time by each flush. They usually
require a minimum water pressure of 25–40 psi to operate well. Such systems are ideal for
heavy use buildings as there is no tank to fill and, thus, no cycle time limit. The flushometer
system requires no storage tank, but requires high volume of water in a short span of time.
Thus, a pipe of minimum length 3/4 inch (19 mm) or preferably 1 inch (25 mm), must be
used, but as the high volume is used only for a short duration, very little water is used for
the amount of flushing efficacy delivered. While the higher water pressure employed by a
flushometer valve does scour the bowl more efficiently than a gravity-driven system, and
while fewer blockages typically occur as a result of this high water pressure, flushometer
systems still require approximately the same amount of water as a gravity system to operate.
3. Pressurized tank
This is a less commonly used new design, which is based on using water line pressure to
achieve a higher flush velocity.
Figure 1 Dual lush toilet with cistern Figure 2 Flushometer type toilet
Water eficient ixtures
Water closets (WCs)
Water closets or toilets can use water anywhere between 13.5–9 litres per flush for the conventional
single flush models. Low flush toilets use on an average 4–5 litres for 6/3 dual flush toilet or even
lesser for the new versions of dual flush model – 4.5/3.
There are three basic types of WCs
1. Gravity tank WC
This comprises of a bowl or pan with a tank connected by a flush pipe. Older versions of this
system use up to 13.5 litres of water for every flush, whereas the latest ones use 4.5 litres for
a full flush.
2. Flush valve operated
This type of toilet uses a flushometer valve directly connected to the water supply plumbing.
This valve controls the quantity of water released over time by each flush. They usually
require a minimum water pressure of 25–40 psi to operate well. Such systems are ideal for
heavy use buildings as there is no tank to fill and, thus, no cycle time limit. The flushometer
system requires no storage tank, but requires high volume of water in a short span of time.
Thus, a pipe of minimum length 3/4 inch (19 mm) or preferably 1 inch (25 mm), must be
used, but as the high volume is used only for a short duration, very little water is used for
the amount of flushing efficacy delivered. While the higher water pressure employed by a
flushometer valve does scour the bowl more efficiently than a gravity-driven system, and
while fewer blockages typically occur as a result of this high water pressure, flushometer
systems still require approximately the same amount of water as a gravity system to operate.
3. Pressurized tank
This is a less commonly used new design, which is based on using water line pressure to
achieve a higher flush velocity.
Figure 1 Dual lush toilet with cistern Figure 2 Flushometer type toilet
