The Board of Water & Light draws all of its water from wells which pump almost entirely from a layer of water-bearing sandstone 100 to 500 feet below the surface called the Saginaw Aquifer. The Saginaw Formation is shielded in most places from direct contact with the surface by layers of clay and shale, so contaminants do not easily get into the water at that level.
There are areas at the surface, however, which directly contribute to the aquifer, and these areas must be protected from contamination. The areas are called Wellhead Protection Areas, and the BWL participates in regional Wellhead Protection Teams which concern themselves with potential contamination of the aquifer through these areas. The Teams also search for and arrange for plugging of abandoned wells which can serve as conduits for contamination to reach the aquifer.
The 128 wells that make up the BWL system pump an average of approximately 21 million gallons per day (MGD) to either of two water conditioning plants . That's a lot of water! However, long-term measurements of the aquifer show that levels have not gone down overall and that the supply will be adequate for many years to come.
All of the well water pumped from the ground goes to one of our two water conditioning plants. The raw well water with an average of 450 ppm hardness is then softened to an average of 98 ppm hardness in the finished water. The water is softened, disinfected and filtered. Reducing the water's corrosiveness is important to keeping lead out of drinking water. The BWL uses a phosphate compound to coat water pipes and prevent leaching of lead and copper into drinking water and which has shown past success in reducing lead levels. The level of corrosion control leaving our Water Conditioning Plants is tested every 4 hours and 30 minutes to confirm that proper levels of the additive are present. Also, quarterly sampling results from the distribution system are used to confirm that the levels of additive necessary to achieve corrosion control are present throughout the BWL's service territory and following treatment, the water is then distributed through underground mains under pressure to our customers. The maintenance of that pressure ensures that when leaks occur, the leakage is of conditioned water out of the main, not of dirty water into the main.
The BWL runs a variety of tests on the raw water, conditioned water and distributed water multiple times a day. Tests for bacteria, softening parameters, inorganic and organic compounds are performed in our laboratories to maintain the quality of your water.
One of the key factors in the maintenance of good water quality lies in the establishment of a disinfectant residual. The Board of Water & Light relies on the use of a type of chlorine called chloramine.
Chloramine has a number of advantages over "free chlorine":
First, it lasts longer. As water travels through mains, it loses its residual much more slowly than it would with free chlorine. That means that less must be applied at the water conditioning plant to achieve a residual near the end of the system.
Second, it imparts very little odor or taste. We are all familiar with the "swimming pool" odor of highly chlorinated water that detracts from its appeal. People seldom notice any odor from chloraminated water.
Third, it results in lower disinfection by-products. Regulated compounds like trihalomethanes and haloacetic acids are reduced by up to 90% compared to waters using free chlorine.
By conditioning the water, the BWL is able to stabilize the water brought to your tap. In maintaining consistency in the conditioned water, we offer you the ability to tailor the water to your use. A Typical Analysis, while not representing actual results at any particular time, gives you an idea of what ranges you might expect for a variety of chemical measurements.
Questions? Call Angie Goodman, Water Quality Administrator at 517-702-7059.