The drain hose may be too far down inside the drainpipe (standpipe) or laundry tub. Drained water can siphon back into the washer if the drain hose extends too far. Make sure that the drain hose does not extend more than 4.5" (113 mm) into the drainpipe or laundry tub. Using the U-shape drain hose form (as described in the Installation Instructions), will provide the correct length of drain hose in the drainpipe or laundry tub.
Do not seal the drain hose into the drainpipe with tape. The drain hose should be loose, yet secure. There must be a gap between the drain hose and the drainpipe to allow air to flow through. The air gap will break the suction. This will prevent water from continuously being sucked out of the machine (siphoning) as it fills.
Check that the top of the drain is at least 30" (76.2 cm) high (as measured from the floor.) If the drain is below 30" (76.2 cm), the water will start to flow out of the machine due to gravity. The flow of water can create suction (siphon) and the water will continue to drain out of the washer.