Water Treatment Process

Plant Flow & Treatment

The Lima Water Treatment Plant receives raw water from five above ground reservoirs. To the west of Lima, water from the Auglaize River is used to fill the 4.9 billion gallon Bresler Lake Reservoir and the new 5.4 billion gallon Williams Reservoir. On the east side, a complex consisting of Ferguson, Metzger Lake and Lost Creek Reservoirs is filled from the Ottawa River. The total storage capacity of the east side complex is approximately 4.0 billion gallons.

The water flows into a 2.5 million gallon primary treatment basin, where clarification and softening chemicals can be added. Water flows from the primary treatment basin into two secondary basins (1.3 million gallons each). Additional softening and clarification chemicals can be added at this stage if needed.

Clarified and softened water leaves the secondary basins and flows to a 40,000 gallon chamber where carbon dioxide is added to stabilize the water. When leaving this stabilization basin, a polyphosphate is added to provide additional water stability.

Water continues through the plant to a bank of ten rapid sand filters. Here, water is filtered through a combination of anthracite coal, sand, and a mixture of support gravel. The filters remove any remaining suspended matter present in the water.

Water leaving the sand filters may then be passed through four granular activated carbon filters to further improve the water quality. The water is then chlorinated, fluoridated, and a second polyphosphate is added to enhance water stability in the distribution system. The water then flows into clear wells for storage until needed in the distribution system. Water is pumped from the clear wells using four electric pumps and one diesel driven pump (in case of power failure) to meet the city's water needs.

Plant operators monitor and control the system using a programmable logic controller (PLC) based computer system. PLCs are also used to control and monitor the reservoir systems.

Water Quality

At the Water Supply and Treatment Laboratory our water supply and finished water are tested to assure that we can meet State and Federal Environmental Protection Agency (EPA) standards. New treatment and testing methods are also researched to prepare for future water quality regulations.

If you have a concern about your water quality, you may call our laboratory. We will be glad to answer your questions and discuss your problem.


To protect you from waterborne diseases, a small amount of chlorine is added to your water at the water plant. According to EPA regulations, a minimum of 0.2 mg/L of chlorine must be present in our distribution system. If you wish to decrease the amount of chlorine in your water (for fish tanks or to refrigerate for drinking) you can fill a clean container, leave it slightly uncovered, and allow it to stand overnight. The chlorine will dissipate. You can speed up the procedure by warming the water in a pan.

Cloudy Water

Cloudy or milky looking water is usually caused by dissolved air bubbles coming out of the water and is harmless. The air bubbles can be caused by pressure changes, temperature changes, water that is too hot (above 140F) and faucet aerators.

If the cloudiness is caused by air bubbles, it will clear in a minute or two from the bottom of the container upwards.

Rusty Water

Rusty water or yellow water occurs when rust deposits are stirred up by an extreme change in water flow in water pipes and main lines. Changes in water flow can be caused when a water line breaks or when hydrants are flushed or used to fight fires.

Rusty water will generally clear up within 2-3 hours after the line is repaired or hydrants closed.

When your water is rusty, it can stain your laundry. If clothes do get stained, keep them moist; obtain a rust remover at the grocery or hardware store and follow the directions on the package. Try not to run your hot water faucet if rust is present since this will draw rusty water into your hot water tank.


All public water suppliers are regulated by the Safe Drinking Water Act to provide information about lead in drinking water.

Currently, the Lima water treatment process reduces the possibility of lead contamination from residential plumbing. There is no lead in the water coming from our treatment plant.