The present disclosure is directed to a backwater valve assembly comprising a main valve body, a flapper sub-assembly, and a cap. The main valve body has an inner wall that can define a recess into which the flapper sub-assembly can be removably secured. The flapper sub-assembly includes at least one flapper element that can pivot between an open position, in which the flapper element allows fluid to flow through the backwater valve assembly, and a closed position, in which the flapper element prevents fluid from flowing in the opposite direction. The flapper sub-assembly can be removably coupled to the cap to allow the flapper sub-assembly and cap to be installed in or removed from the main valve body together as a unitary assembly.

A system for protecting a fluid supply from a contaminant includes an anchor check valve having an inlet end and an exit end, the anchor check valve adapted to allow fluid flow through the anchor check valve from the inlet end to the exit end but prevent fluid flow through the check valve from the exit end to the inlet end; a dry-barrel fire hydrant in proximate fluid communication with the anchor check valve, the dry-barrel fire hydrant having a valve operating mechanism; and a hydrant shoe coupled to the anchor check valve, the hydrant shoe having a valve assembly adjustably connected to the valve operating mechanism of the dry-barrel fire hydrant.

A blocking valve has an outer valve body housing a weighted paddle, the weighted paddle having a narrow upper portion with a hitch groove and a wider lower portion, the weighted paddle rotatable around a horizontal pivot, the weighted paddle to lie in a horizontal position during an active flow of liquid and to rotate to a vertical position with the upper portion above the lower portion when the flow of liquid is stopped, and a locking mechanism to engage with the hitch groove to lock the weighted paddle into a vertical position and to block the active flow of liquid when the active flow of liquid is resumed.