An Analysis of City Water and Community Water Supplies
In this continuing series of Blogs we are discussing water, water quality and various treatment methods that city and community water supplies use to treat their water before it is delivered to your home. Today we are looking at the city of Howell, MI and the community wells that supply water to its 9400 residents.
Communities that use well water as their primary source of water have many different issues to address as it relates to their water. As discussed in previous blog posts, the water chemistry from every well can vary widely. Most of these community well supplies will have several different water wells from which their water is drawn from. The number of wells needed is dependent on the size of the community and water volume needed to service that community. This takes into account the average daily usage per household and also peak periods of water usage along with the potential usage for firefighting.
The city of Howell has six different wells from which water is drawn. These wells are up to 400 feet underground. This is done to protect the water supply, to assure adequate water supply for future use and to assure some stability in the water chemistry. IE: Hardness, Iron, Manganese, Arsenic, Radium, Etc. The Howell water treatment facility has a 620,000-gallon ground storage reservoir along with a 300,000 elevated storage tank to service its 9400 residents and firefighting needs.
The Howell water treatment plant employs a method of “Lime Softening” to treat the water. Limewater (Calcium Hydroxide) is introduced into the water supply at the treatment plant which reacts with the Calcium and Magnesium (Hardness) in the water causing it to “floc” or fall out of the water. The hardness falls out as scale and then is filtered out of the water. This method of water treatment has actually been used since the 1800’s and was originally used in London, England to treat water drawn from the Thames River. Some of the primary reasons this method is used by community water supplies today are to control Arsenic, Iron, Manganese and Radium that may be present in the water supply as it is drawn from the ground. Sulfuric Acid and Polyphosphates are added, after initial treatment, to control the PH and stabilize the water. Chlorine is added, as a disinfectant, as the water is sent to the reservoir tanks.
All community and municipal water supplies have to abide by the National Drinking Water Standards. Arsenic is one of many contaminants regulated by these standards as are chemicals used to treat the water supply along with the by-products created when using disinfecting additives like chlorine. Fluoride additives such as Hydrofluosilicic Acid have become an increasing topic of discussion and concern as many current studies have shown negative long-term effects from these additives. Many cities across the US are now choosing to not add fluoride supplements to their water supplies.
The Howell water treatment plant adds calcium hardness back into the water supply before it leaves the treatment plant. This brings the hard water levels back up to 6-7 grains per gallon. Six to seven grains per gallon of hardness is low compared to the 15 to 30 gpg of hard water most homeowners have that live on a private well in Livingston County. Although 6-7 gpg of hardness may seem relatively low on the hardness scale, with a family of three people, on the water that is 6gpg of hardness, in one year that family will have nearly 94 Lbs of rock that has gone through their household!
How is this! In one year 657,000 grains of dissolved rock (Hardness) will have gone through this home! 7000 grains per gallon of hardness is equivalent to 1 lb of rock in the water. Therefore 93.86 lbs of rock will have gone through all the appliances, water heater, plumbing and fixtures in one year! So it is easy to see that even at relatively low hardness levels there are still major concerns with hard water problems along with chlorine and other things added to the water supply.
More information regarding topics discussed in this article is available in the links below.
- City of Howell, MI 2013 Water Report
- National Primary Drinking Water Standards
- Fluoride Information
- Disinfectants in Drinking Water
- EVRCS Water Treatment Solutions
- Reverse Osmosis Water Treatment Solutions
Good days and good water to you!