Household Water Supply

1
Household Water Supply
2
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 supplyparallel 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
3
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
4
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)
5
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.
6
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.
7
(No Transcript)
8
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.
9
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
10
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.
11
Bored wellsA 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.
12
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 dont
need pumps.
13
Wells
14
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
15
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
16
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
17
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.
18
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.
19
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!
20
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.
21
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.
22
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
23
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
24
The run of pipe (how long it is) and the rise
(how high up it goes) doesnt matter as long as
you have sufficient pressure. If there isnt
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.
25
ActivityUsing 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