Preska Water Softener Repair

Unexpected system failure causes skin irritation for some residents

January 27, 2021 |


On Friday afternoon January 22, the University was contacted with a concern about water quality in Preska Residence Community.  A student reported that she was experiencing a skin rash after showering.

The University contacted Mankato’s water treatment chemists, who responded Friday evening.  Testing performed revealed normal levels of alkalinity, pH, and chlorine, but revealed that the building’s water softener system had failed.

The water softener system was repaired on Monday, January 25.  The building’s water tank was flushed, and the water hardness, counted in parts per million (ppm) is now testing in a normal range. 

More Detail

At 4:30 pm on Friday, January 22, the University’s Environmental Health and Safety Director (EH&S Director) received a call from a Preska resident and her family regarding a rash she was experiencing after showering.  The EHS Director contacted chemists at the Mankato Water Treatment Center, who responded later the same evening to collect water samples. 

City results were received on Saturday morning. The hot water at the student’s shower measured 170 ppm  - Friday evening sample.

This number was unexpectedly high, as the building’s water softener system would typically yield a measurement of under 20 ppm. University plumbers found that the water softener system had failed, and they made repairs on Monday.

They flushed the building’s water tank on Monday.  This removed un-softened water and filled the tank with softened water.  Water is now testing at 17-20 ppm.

Hard Water 101

Water hardness is a measure of minerals in the water – calcium carbonate and magnesium. These are measured in ‘parts per million’ or ppm. Water leaves the Mankato water treatment plant at 183 ppm.

Water softeners remove these minerals. Removing the minerals prevents build-up in plumbing systems and prevents skin irritation.   

People may experience dry skin between 60-120 ppm. The University’s water softeners are installed in each building.  They are set to achieve below 20 ppm.

How the University’s Water Softeners Differ from a Home Water Softener

A home’s water softener is typically treating the water as it enters the home – both the hot and cold water are treated. People often prefer the taste of hard water; plumbers make adaptations in some homes so that hard water is available as drinking water.

At the University, the hot water is softened.  The cold water is not softened.  Cold water in a University building is typically in the 170 ppm range. At the shower valve – the water is 170 ppm on the cold side and 0-20 on the hot side.  Same set up everywhere on campus.

The water softener system in Preska serves Preska J, K and L.  There is one tank and one water softener system for the building.  Preska I Hall is served by a separate tank. 

Can I drink the water?

The water is safe to drink. People typically prefer the taste of hard water.  The water was safe to drink while the water softener was not working. 

Filtered water is available at the sink in each floor kitchen and at water bottle filler stations on lobby ice machines and water fountains.

Were Experts Consulted?

The University’s Environmental Health and Safety Director consulted with the City of Mankato water treatment chemist and the State of Minnesota Certified Industrial Hygienist.

What Testing was Done?

Testing by the Mankato water treatment chemist found normal levels of alkalinity, pH, and chlorine. Initally, high water hardness was found (see section above).

Testing now shows below 20 ppm (see sections above).

Share this Article: