It is widely recognized that installation of any of the above mentioned backflow preventers is space consuming, increases the pressure drop in the fire protection system, and is costly. Retrofit of these devices into existing fire protection systems can be particularly challenging. The installation of both an alarm check and a backflow preventer can be considered redundant, pressure consuming, and a costly overkill. Protection of the potable water supply is the overriding issue. One attempt has been made in this area by the Viking Corporation - a combination alarm check and RP device was produced but was unsuccessful in obtaining USC approval.
More work is needed.
While this smacks of apple pie and motherhood, hopefully we will all live long enough to see it to fruition. In summary, backflow devices are installed in fire lines for all the above reasons and to ultimately protect the potable water supply. In addition, their use is mandated by many state legislative authorities, and water superintendents are required to use them. The water supplier is responsible for water quality from reservoir to tap.