Spring Ball Check Valve (3D Printable, Modular)

This is a simple yet very effective check valve that prevents water from flowing back into the barrel or through the pump when it is not running. The principle is based on a 10 mm stainless steel ball that is pressed against the opening by a stainless compression spring (length 20 mm, spring diameter 9 mm, wire diameter 1 mm). The spring keeps the ball sealed against the water. When the pump starts or water pressure increases, the ball is pushed back and allows water to flow freely. The valve consists of two screw-together parts – male and female – which hold the spring and the ball inside. For proper function, it is necessary to insert a stainless spring and a stainless ball (both are inexpensive and can be ordered from Temu, Aliexpress, etc.). 👉 On the body of the valve there is a small marking “IN” and “OUT” with an arrow, so that when assembling the male and female parts, you can easily see which side should be connected to the barrel and which side to the pump. Since people often