a the water in the collection chamber is so low that the pivot valve disc 15 hangs almost straight down since the only force on the valve is that of gravity referring next to fig1 b the water has begun to rise causing the disc to rise toward the valve seat the water rises further in fig1 c as the valve continues to close and finally in fig1 d the water has risen above the level of the check valve so that the valve has closed completely although fig1 a through d depict only a single check valve the valve wall contains an array of such valves in the preferred embodiment the valves occupying about 50 of the wall area the proximity of the valves to each other is limited only by the need to maintain the strength of the wall in the face of recurring blows of the waves as they impinge on the wall clearly the valve wall 39 s strength is diminished by each wall aperture 113 formed in the wall each check valve will open when the pressure on the wave exceeds the pressure on the holding tank side or when the water level in the collection chamber side falls below the level of the check valve the net result is that the collection vessel will continue to fill by the action of the waves against the valve.