| Install a backflow valve to prevent sewer backup from coming into your home. |
| Veins in the legs have valves which normally prevent any backflow of the blood on its way towards the heart. |
| Reduced pressure backflow preventers are more expensive, used mostly in commercial irrigation installations. |
| The lymphatic vessels, like veins, have one-way valves that prevent backflow. |
| Incorrectly installed systems can waste water and care must be taken not to contaminate mains water supplies through backflow. |
| Venous ulceration occurs when the valves inside the veins become incompetent, leading to backflow and congestion of venous blood. |
