Tanks and reservoirs have typically been designed
and operated to satisfy hydraulic purposes, such as
emergency storage, with water quality issues having
largely been ignored. But water quality issues are
actually important considerations in the design and
operation of distribution system tanks and reservoirs.
Mixing and aging, for example, are two related phenomena
that can affect water quality-long residence
times depress disinfectant residuals and can promote
bacterial regrowth, and uneven mixing can result in
zones of older water. Minimizing detention time and
avoiding parcels of water that remain in the storage
facility for long periods of time should therefore be
implicit objectives in the design and operation of distribution
system storage facilities. Monitoring techniques
and models are available that can help to assess the
potential for water quality problems in tanks and reservoirs,
and relatively straightforward designs, retrofits,
and operational solutions exist to help eliminate or
reduce the potential for water quality problems in the
distribution system. This study resulted in practical
solutions that, in many cases, can easily be
implemented to reduce problems with water quality
and protect public health. Includes 20 references, figures.