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Small Water Systems Pump Controls
For more information
Northwest Regional Office Kent (253) 395-6750
Southwest Regional Office Tumwater (360) 236-3030
Eastern Regional Office Spokane (509) 456-3115


Pump Controls regulate source production to maintain adequate flow rates and water pressures. Water systems
adjust their control systems to maintain:


A minimum pressure of 30 psi in the water distribution system.

A minimum pressure of 20 psi during fire flow conditions.

Adequate water levels in storage tanks and pressure vessels.

Adequate free chlorine levels in systems that require chlorination.

Adequate protection of pumps and electrical equipment during emergencies, such as power outages, water
outages, voltage fluctuations and equipment malfunctions.

Many small water systems have a single-source well with a submersible pump controlled by a pressure switch.
The pressure switch senses pressure in the supply line. When line pressure drops, the pressure switch signals the
pump control box to start the well pump.

Control System Pressure Switch and Bladder Tank
The bladder tank (11) contains pressurized air and water separated by a membrane called the bladder. As water
pressure changes, the volume of air contracts and expands triggering the pressure switch (4) on or off. This
provides a buffer to minimize pump cycling and protect against water hammer
.





























Drinking Water Tech Tips:
Small Water Systems Pump Controls


Pump Motor HP Model
Main Power and
Breaker Box
Pressure
Switch
Bladder Tank
To Distribution
System
Gate Valve
Pressure
Relief Valve
Pressure
Gauge
Pump
Control
Box
Submersible
Pump
Pitless

Unit

Source Water

Sample Tap

Check
Valve
Digital Flow
Meter

Ball Valve
Lightning Arrestor
Sample Tap
DOH PUB #331-401
March 2008
2

(1) Main Power and Breaker Box protect controls, electrical components and pumps from over-amperage. It is
installed where electrical power enters the pumphouse. The manual pull-down switch turns the power on and off.

(2) Lightning Arrestor protects the pump motor and controls from voltage surges caused by lightning,
switching loads and power line interference. These do not protect against a direct strike.

(3) Pump Control Box protects submersible pumps from low or high voltage, a drop in water level, low yield
wells, clogged well screens, malfunctioning pumps and motors, and rapid cycling. Pump control boxes usually
have microprocessors that monitor power-line voltage and pump motor power draw.

(4) Pressure Switch senses pressure in the water line and signals the pump to start and stop with pre-set low and
high pressure settings. Pressure switches can control well pumps and booster pumps. Proper high and low
pressure settings allow multiple pumps to operate in lead and lag mode.

(5) Digital Flow Meter measures the flow rate in gallons or cubic feet per minute. It usually indicates the total
volume produced since the meter was installed. Systems use this information to monitor water production, detect
distribution leaks and pumping problems, and determine peak demand.

(6) Check Valve allows water to flow only one direction. Submersible well pumps require spring loaded check
valves to maintain system pressure and prevent backflow of water from the system into the well.

(7) Pressure Gauge measures static pressure in the water line.

(8) Pressure Relief Valve protects the pressure tank and water lines from catastrophic failure due to over-
pressure. The valve opens when water or air pressure exceeds a pre-set level, usually 100 psi. The discharge line
should be directed outdoors or to a location where water will not damage property or injure people.

(9) Ball Valve has a lever to open and shut the ball-shaped valve and is more reliable than a gate valve. It is
more likely to actually open and close after years of use.

(10) Gate Valve opens by lifting a round or rectangular plate out of the water flow. Gate valves are designed to
operate fully opened or closed and are not well suited to regulate flow. When fully open, the typical gate valve has
no obstruction in the flow path, resulting in very low friction loss.

(11) Bladder Pressure Tank contains pressurized air and water separated by a membrane, the bladder. As water
pressure changes, the bladder contracts and expands providing a buffer to minimize pump cycling and protect
against water hammer.

(12) Source Water Sample Tap used to collect a water sample directly from the source.

(13) Sample Tap used to evaluate water quality and possible sources of system contamination. 3

Control System - Storage Tank Water Levels

Storage tanks provide additional capacity to meet peak demand and, in some cases, provide emergency supply
when the well pump is not available. Gravity or booster pumps draw water from the storage tank into the
distribution system. Pressure switches sense pressure in the supply line and signal the booster pumps to turn off or
on at preset levels.












































Well Pump
As the water level in the
reservoir rises or drops,
sensors (
Electrodes,
Float Switches
or
Pressure Transducers
)
signal the
Water Level
C<b>ontrol B<b>ox
.
The
Water Level Control Box

signals the
Pump Control Box
to
turn the well pump on or off.
Submersible Well
Pump
OR
Well Pump
Stop
Well Pump
Start
High Water
Level Alarm
Low Water
Level Alarm
Well Source Water
Chlorine
Solution
Well Pump with Chlorine Feed Pump
The pump control box turns the well pump
motor and the
Electrical Outlet
on or off
when the water level control box signals it.
The
Chlorine Feed Pump
runs when the
electrical outlet has power, adding chlorine
solution to the source water entering the
reservoir.
Water Level
Control Box
Electrical
Outlet
Chlorine Feed Pump
Chlorinated Water
To Distribution
Reservoir with water
level sensors
OR
Electrodes

in Reservoir
Float Switches

in Reservoir
Pump Control

Box

Power
Meter
Main Power
Supply Box
3 - 5 HP Submersible
Pump and Motor
Water Level
Control Box
Well Source Water
Well Pump
Stop
Well Pump
Start
High Water
Level Alarm
Low Water
Level Alarm
Water to
Distribution 4


Common Controls


Hands-Off-Auto (HOA) Switch allows the system to operate in manual or automatic mode. Some devices allow
multiple wells or booster pumps to alternate, or to operate individually, in lead or lag mode, or on emergency
power.

Pump Alternator automatically alternates the operation of two or more pumps.

Constant Pressure Pump Controllers maintain constant pressure by changing the speed of the pump motor.
Special pump motors, called variable frequency drives (VFD), are needed for this arrangement.

Submersible Pump Motor Protectors protect motors from high or low voltage, excessive pump cycling from
waterlogged tanks, under or overload, overheated motors, or drop in water level. They may be mounted in the
pump control box or HOA.

Pump Motor Starters provide a temporary power boost to start high voltage motors. They may be mounted in
the pump control box or HOA.

Flow Switches sense water flow and send a signal to control pumps, such as chemical feed pumps. They may
work with a programmable logic controller (PLC) to provide proportional addition of a chemical, such as a chlorine
solution.

Water Level Float Switches or Electrodes turn equipment on or off or signal alarms based on water levels.

Emergency Power Manual Switch switches power from the main power supply to an emergency generator.

Well Low-Water-Level Sensors turn off the well pumps when water drops below the lowest sensor. Power is
not restored until the water level reaches the upper sensor.

Solenoid Valves automatically open and close valves.

Pump Run Hours display the total number of hours a pump has been running.