Two Kinds of Filtration
When the MDC was established in 1929, the region’s water was filtered at a state-of-the-art slow sand filtration facility that is still in use at the West Hartford Reservoir. Over the years technology changed, and in the early 1970s the MDC built a rapid sand filtration facility at Reservoir 6. Today, both facilities produce the same high quality water. They just do it a little differently.
East Hartford, Hartford, Newington,
Rocky Hill, West Hartford and Wethersfield
(portions of Farmington, Glastonbury and Portland).
Slow Sand Filtration
The slow sand filtration system at the West Hartford facility has 22 underground filter beds, some as large as a football field. Raw, untreated water is piped directly from the reservoirs to each bed for cleaning. Because the water is not pretreated, the filtration process is relatively slow. Nonetheless, the size of the facility enables about two-thirds of all MDC water to be filtered here.
Bloomfield, Entrance off of Route 44 in West Hartford
Bloomfield, East Hartford and Windsor
(portions of Glastonbury, South Windsor and East Granby).
Rapid Sand Filtration
The Reservoir 6 rapid sand system combines chemical treatment with filtration at six small filter beds. Pre-treating the water before it is filtered removes most of the impurities. Because of this, any remaining impurities can be removed by filters at a rate 32 times faster than at West Hartford. That is why the process is called rapid sand filtration.
About the Sand
The filters in the MDC’s water treatment facilities use a combined 50,000 tons of special quartz sand, usually from New Jersey and Rhode Island. The sand, which measures 1/75th of an inch in diameter, captures both solids and microscopic bacteria suspended in water.