The process of transmitting and distributing drinking water to Mankato customers begins as the clean water leaves the Water Treatment Plant. From the Water Treatment Plant, water is pumped into the distribution system which is connected to five ground storage tanks and two elevated water towers. The combined storage capacity is 11 million gallons of water. These storage tanks also serve as the source of the system's water pressure, which usually ranges from 65 to 85 psi. 

The distribution water mains are made out of cast iron, ductile iron and PVC. They range in size from four inches to 36 inches. The majority of water mains connected to residential homes are eight inches in size.

The City of Mankato devotes substantial time and resources each year for the maintenance and repair of the water distribution system, water valves and fire hydrants. The City’s maintenance program is designed to provide customers with the finest quality of drinking water and necessary water volume for fire protection.

What is seen when City crews are working on the water distribution system and what they might be doing:

1. Fire hydrant maintenance 
2. Fire flow testing  
3. Water main valves 
4. Water main repairs 
5. Water loss survey 

Fire Hydrant Maintenance
The City of Mankato has approximately 1,900 fire hydrants that the Utilities Division is responsible for maintaining. Maintenance includes testing for proper operation, performing necessary repairs, flushing the hydrants twice a year and keeping them free from any obstructions, such as vegetation or landscaping that may impede the use of the hydrant.

Fire Flow Testing
Whenever a new business requiring an internal fire sprinkler system is to be built in Mankato, a fire flow test is performed on the distribution system to determine if there is enough water volume and pressure to adequately protect the building. The City of Mankato has an ISO 3 fire protection rating. Which means that Mankato is ranked among the highest in the State. It testifies to the positive working relations and long-term planning between Public Works and Public Safety. In addition, this high rating results in potential savings for residential and commercial property owners' fire insurance premiums.

Water Main Valves
When water main breaks occur, valves are used to turn off the water so that repairs can be made. If the valves closest to the main break are inoperable, other valves must be closed, necessitating the interruption of water service to additional customers. To reduce the likelihood of this occurring, the City of Mankato distribution system has an on \going maintenance program to determine where older valves should be replaced and where the installation of additional valves would enhance system control. All of the City’s 5,427 valves are operated once every five years to ensure they are operating correctly.

Water Main Repairs
Occasionally a water main will start to leak. The most common cause is ground movement during the freeze/thaw cycle of winter. This causes the water main to break in the form of a crack around the pipe. The pipe is repaired with a stainless steel sleeve that is wrapped around the pipe and bolted together to seal the entire leak (see picture).
Other causes of water leaks are corrosion to the water main and the bolts that hold the fittings together. Leaks can also develop on the water service lines that are connected to the customer.

Water Loss Survey
The primary purpose of this program is to insure that our natural resources are not being wasted. Each year, Utilities has an ongoing water loss survey program. This program consists of several components: 

• Monthly monitoring of the amount of water that is produced by the Water Treatment Plant and compared with the amount of water that is used by customers. 
• Each year, the City has an independent contractor perform a water loss survey. It consists of using sensitive listening devices, designed to hear the noise frequency that water makes as it is leaving the pipe under pressure. This sounds much like the noise heard in a home when running water.  
•  Distribution crews also use the sensitive listening devices and monitor specific areas throughout the year.