Sources of Salt Water-

Salt can be found in water almost anywhere in Maine. There are three reasons that you might find salt in your water.

1. Intrusion from the ocean
2. Contamination from road ice melting chemicals
3. Confined aquifer that has salt.

Salt Water Intrusion

The fresh water floats on top of the salt water. As the fresh water is removed and the hydrostatic pressure it creates is decreased, the salt water come farther into the aquifer.

If you live on the coast and have a new well drilled, the driller will usually check the water to see if it has a high content of chlorides or a high total dissolved solids (TDS). Either of these conditions will indicate the presence of salt in the water. Because the salt content may change with time, the home owner should continue to monitor one of these parameters as he begins to use the well. Salt water may move into the well as fresh water is being removed. This replacement with salt water is called intrusion. Pumping the well harder(removing the water at a higher rate) can make the problem worse(see the picture above). Before any decisions are made about treating the water, the water should be used long enough to get a stable reading of either chlorides or TDS. If either of these parameters (chlorides or TDS) rise, the concentration of salt is rising. If the concentration of salt continues to rise, a different source of water may be suggested. If the well is abandoned, it should be sealed to prevent possible further pollution of the remaining aquifer. Check with Maine's Drinking Water Program (DWP), Department of Environmental Protection(DEP), or the fact sheet from New Hampshire's Department of Environmental Services (DES) for help in determining how to properly abandon a well.

You can have a well contaminated from the chemicals placed on the highways that melt salt. If you suspect this to be the problem, you should contact the Maine Department of Transportation (DOT) and if you happen to live near the Turnpike you should contact the Maine Turnpike Authority (MTA). They can do further testing to see if the salt is a result of roadway pollution. They will check for concentrations of chemicals that are not normally found in ground water and can tell from these concentrations if the pollution is coming from the highway. If the salt is the result of highway contamination, they will likely either provide a new well or treat the water in the existing well.

There are areas in Maine that have natural pockets in the bedrock that have salt water. These types of confined aquifers are rare but do occur. These wells even if treated may run out of water as they tend to recharge very slowly. You may want to consider a new well or at the very least pump the well to see what the recovery will be.

Treatment

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The only practical treatment for a home that has a well with salt water contamination is with a reverse osmosis(RO) system. These systems pump water at a high pressure against a semi-permeable membrane and force water through the membrane leaving the salt with some of the water to run down the drain. These systems require the well produce more water than is actually used because the salt must be carried away with a portion of the water. A well designed system can recover 50% or more of the water in the well. When purchasing one of these systems you should carefully consider the experience of the company designing and installing the system. Their experience is as important as the quality of the equipment. You may want to take a look at "How to Purchase a Whole House RO".