Transcript Water Supply File

Household Water
Supply
The water supply in a house is a managed pressure system
Pipe sizing is used to control pressure in the distribution throughout the house
Valves are used to control supply at critical points, for example a valve is installed at the point of
connection to all water appliances so that they may be serviced without shutting off the water
supply to the house.
Compression chambers are used to control pressure fluctuations at critical points, for example at
faucets to prevent water hammer
Two basic branch distribution methods are employed for water supply—parallel and series. Either
one may be used, and in some instances both are used simultaneously in the same branch
Identify and describe the function of
Rural water supply
Water main (or well)
Types of wells that can supply water
Possible pumping sources to deliver the water
Types of storage tanks for well systems
Municipal water supply
Main water line and control valve
Cold water supply
Hot water supply, including heating system
Pipe runs and rises
Stops, valves and faucets
Describe what happens when “water hammer” occurs. Explain how an air chamber dampens this
phenomenon.A suitable entry should be made in the student work log
1. Municipal Water Supply Systems
Water is vital to everyday life, and throughout history
people have devised systems to make getting and
using it more convenient. Early Rome had indoor
plumbing, meaning a system of aqueducts and pipes
that terminated in homes and at public wells and
fountains for people to use.
Modern water supply systems get water from a variety
of locations, including aquifers, lakes, rivers, wells,
desalinated seawater, and other sources. The water is
then purified
For many municipalities large ponds or lakes are used
as water sources.
Most systems work in a similar fashion to what is
given below.
A large pipe extends out into the lake to a large
concrete and metal structure on the lake bottom which
acts as the intake filter. This filter screens out only the
largest of debris, including wood or large rocks. A set
of large electric submersible pumps in a pump house
building on the shoreline suck the water into a system
of sand and other filters to screen out large and small
debris, including fish, leaves, or gravel.
(Bay Bulls Big Pond pictured in background)
The water then is pumped through a set of pipes
where it is chlorinated to kill bacteria and any small
multicelled organisms that manage to make it
through the filters. The water is then fluoridated to
benefit public dental health.
Finally, the water is tested by various sensors to
determine if it is safe to drink, and pumped to other
locations.There are various pumping stations
throughout the region that supply a constant water
pressure to the areas it serves. Water pipes lead to
almost every house and business in the area, as well
as to fire hydrants.
2. Ground Source Water Wells
In some areas there is no municipal water system. To
get fresh water, wells must be used.
Some precipitation that falls to the ground surface
infiltrates the ground and becomes groundwater.
Groundwater is defined as sub-surface water that fills
openings and pore spaces in soil and rock layers.
Below the ground surface is an unsaturated zone
which water travels through to reach lower zones.
The water table is the point at which the ground is
completely saturated. Below this level the pore spaces
between every grain of soil and rock crevice
completely fill with water.
Types of wells
An aquifer is a layer of sand, gravel or
sediment that contains water that can be
used as wells.
Dug Well
We can dig shallow wells (Dug Well) that
tap into the upper part of the water table.
These were commonly used in days prior to
heavy machinery. If something affects the
water table these can dry up from time to
time. You need to ensure that there is water
available close enough to the surface prior
to starting to dig. Since these are usually
dug by hand or using smaller excavating
machinery they are seldom more that 30
feet deep.
Driven wells are still common today. They are
relatively inexpensive. They are built by driving a
small-diameter pipe (well-point) into soft earth,
such as sand or gravel. This is done by using a
sledge hammer or a mechanical hammer of some
sort. Pipe is added as it gets further in the
ground. A screen is usually attached to the bottom
of the pipe to filter out sand and other particles.
Problems? They can only tap shallow water (50 or
60 feet below ground), and because the source of
the water is so close to the surface, contamination
from surface pollutants can occur.
Types of well-points
Drilled wells obtain water from deep
groundwater aquifers. Drilled wells are
typically about 45 m (150 ft) deep and have a
diameter of 15 cm (6 in). If they are properly
constructed and maintained, they are not as
likely to have contamination, but because of
their depth they may have mineral or
chemical additives that could affect the quality
of your water. Chemical testing should be
conducted on every new drilled well. The
Water Resources Act states that a provincially
licensed well driller must construct all drilled
wells.
Bored wells
A bored well is constructed when low yielding
groundwater sources are found relatively close
to the surface, usually under 30 m (100 ft.).
Bored wells are constructed using a rotary
bucket auger. They are usually completed by
perforating the casing or using a sand screen
with continuous slot openings.
One advantage of bored wells is the large
diameter of the casing, from 45-90 cm (18-36
in.). It provides a water storage reservoir for use
during peak demand periods. A disadvantage of
utilizing a shallow groundwater aquifer is that it
relies on annual precipitation for recharge.
Water shortages may occur following long dry
periods in summer and extended freeze up
during winter months.
We commonly call these deep wells artesian wells. A true artesian
well is flowing, which means there is pressure in the well so that you
don’t need pumps.
Wells
With most wells a pump has to be installed in order to get the water to
where it is to be used. There are a variety of pumps depending on the
type and depth of well you have, distance from source to building,
amount of usage and maintenance of the pump.
First you must determine what your water usage will be then find the
right pump and storage tank combination to ensure you always have
adequate water supply at the right water pressure.
There are two categories of pumps:
Shallow-well pumps which are above ground and Deep-well pumps
which are installed inside the well casing
Wells less than 25’ are called shallow. The shallow-well pump, also
called a lift pump, is at ground level and work by creating a vacuum and
sucking (lifting) the water out of the well. There are four main types of
this pump. These all have a motor attached to drive the action inside.
Reciprocating Pump – Uses a piston that moves
back and forth in a cylinder to create a vacuum.
Centrifugal Pump – Uses a spinning metal disk
called an impeller to throw water off the outer edge
to create the vacuum.
Jet Pump – Also uses an impeller but has
a jet or ejector that acts to improve the
vacuum and amount of water moved.
Rotary Pump – This pump uses a
helical rotor to create the vacuum that
draws the water
For wells deeper than 25’ a pumping device must be installed
near inside the well-casing near the water table. The pumps
are similar to and work in the same way as shallow-well pumps
but they must push the water up the well. The four types are:
The reciprocating pump – uses a piston that
drops into the water and pushes the water up the
pipe.
Centrifugal Pump – a submersible pump that
uses impellers to push the water up to the tank.
Jet Pump – only the ejector in this pump is
submersed. The pump forces a small amount
of water through a venturi tube which forces a
larger amount of water up the pipe.
Helical Pump – Can lift water up to 500’. Works
in a similar manner to the shallow-well rotary
pump
With any water system it is important to
maintain a steady supply of water at a steady
pressure. Municipal water systems will use
pumping stations or water towers which are
large elevated water tanks.
In the case of a privately owned water supply a
tower is not feasible. A hydro-pneumatic tank can
be used. These tanks contain water and air. As
the water is pumped into the tank the air pressure
increases. The pump shuts off once the pressure
reaches a certain level (about 50psi). When you
open a valve in your house (sink, shower, etc) the
air forces the water out of the tank and into the
water lines.
Once we have the water flowing to our homes what happens
then?
As the water comes into our homes smaller sized piping is
used. Typically the pipe from the main water supply to our
homes is ¾” to 1” in size. Once inside the home the pipe size
is reduced as it goes to the various fixtures. Typically ½”
piping is used. As the pipe is reduced in size it increases the
pressure of the water in the system. Constant water pressure
is important so that we get water where we need it, when we
need it in our buildings.
We control the water in our homes through a variety of
valves. In a municipal system every home has a water main
shutoff valve. This valve is owned by the city/town and can
be shutdown if there is trouble with water in the building or
if your bill is not paid!
Within the home itself it is important to have valves placed at
strategic locations. This will ensure that if one part of the system
needs to be shut down the other parts can still function.
There are a variety of valve types. Here are a few:
Ground key or stop valve has a hole through the center and
can be shut off with a ¼ turn.
The gate valve uses a screw mechanism that puts a gate in
place to shut off the water supply.
A compression valve uses a screw mechanism that pushes a
rubber washer over a hole to stop the flow.
Since different people like different water temperatures and
certain appliances need different temperatures of water we
adjust the water temperature through the use of valves
called faucets. The faucet allows us to mix the hot and cold
water to obtain the temperature we want.
The water that comes into our homes is cool fresh water. Once
inside certain fixtures and appliances will need this cold water.
But we also need hot water for bathing, clothes and dish washing,
etc. We use a water heater to heat the water then distribute it to
where it is needed.
Parallel Distribution System
Various fixtures in the building
Main Water line
Hot water tank
Once inside the home or building the supply systems
may be installed with branch circuits in series or in
parallel, or a combination of both. The manner of
distribution affects pressure, rate of flow, and how long
it takes for hot water to reach a particular appliance.
The ideal for water flow is to have shorter paths.
From water main
Various fixtures in the building
Hot Water Tank
Series distribution
The run of pipe (how long it is) and the rise (how high up it goes)
doesn’t matter as long as you have sufficient pressure. If there isn’t
enough water force at a certain point this may be remedied by
increasing the pressure on the system. The balance comes in not
having too much pressure in one part and not enough in another.
Typically homes will have sufficient
pressure from the system they are
on. This can be controlled through
the placement of fixtures and the
sizing of pipe. Larger buildings
may have to have pumps at certain
points to increase the pressure
where needed. Some high rise
buildings will pump water to
holding tanks at the top of the
building and use gravity to
produce the pressure needed.
Activity:Using the book Modern Plumbing Ch. 11 by
Keith Blankenbaker complete the following:
Explain the four types of wells. p.171
How is pressure maintained in a water supply system?
(municipal and well)p. 183
What is the purpose of valves in a water system? P. 245
What is water hammer and how can it be controlled?
p. 107 & p. 348
Describe two types of pumps.
Describe two types of valves used in a plumbing system