New Jersey American Water will temporarily change their water treatment process to perform routine maintenance starting on April 18.

New Jersey American Water says they will resume using chloramines in water treatment at its Raritan-Millstone and Canal Road Water Treatment plants. Parts of Essex, Hunterdon, Mercer, Middlesex, Somerset, Morris, and Union counties will be affected. The changeover is expected to last two months.

The water services company says during the transition to free chlorine residual, some customers may notice a slight chlorine taste and odor in their water. With the resumption of the chloramine process, the taste and smell of chlorine will subside, the water services said.

In mid-February, as part of an annual routine maintenance program for its water distribution system, New Jersey American Water temporarily changed the water treatment process from a chloramine residual (a combined residual) to a free chlorine residual. The water services company says chloramines have long been an effective method of water disinfection that meets all EPA and NJDEP drinking water standards and have been used by New Jersey American Water since the 1980s.

(Communities with an asterisk purchase water from New Jersey American Water.)

Essex County: Irvington, Maplewood, Millburn

Hunterdon County: Flemington Borough*, Raritan Township, Readington Township, Tewksbury Township

Mercer County: Hopewell Borough*, Hopewell Township, Lawrence Township*, Princeton Borough, Princeton Junction, Princeton Township, Trenton*, West Windsor Township

Middlesex County: Cranbury Township, Dunellen Borough, Edison Township, Jamesburg Borough, Middlesex Borough, Monroe Township, North Brunswick*, Piscataway Township, Plainsboro Township, South Brunswick Township, South Plainfield Borough

Morris County: Chatham Township, Florham Park Borough, Long Hill Township, Mendham Township, Mendham Borough

Somerset County: Bedminster Township, Bernards Township, Bernardsville Borough, Bound Brook Borough, Branchburg Township, Bridgewater Township, Far Hills Borough, Franklin Township, Green Brook Township, Hillsborough Township, Manville Borough, Millstone Borough, Montgomery Township, North Plainfield Borough, Peapack & Gladstone Borough, Raritan Borough, Rocky Hill*, Somerville Borough, South Bound Brook Borough, Warren Township, Watchung Borough

Union County: Berkley Heights Township, City of Rahway*, Clark Township, Cranford Township, City of Elizabeth (Liberty)*, Fanwood Borough, Garwood Borough, Hillside Township, Kenilworth Borough, Linden City, Mountainside Borough, New Providence Borough, Plainfield City, Roselle Borough, Roselle Park Borough, Scotch Plains Township, Springfield Township, Summit, Union Township, Westfield Township, Winfield Park Township*