| Venous ulceration occurs when the valves inside the veins become incompetent, leading to backflow and congestion of venous blood. |
| Install a backflow valve to prevent sewer backup from coming into your home. |
| Other problems would be backflow into the system or a rising groundwater table that would allow seepage into the collection system. |
| Reduced pressure backflow preventers are more expensive, used mostly in commercial irrigation installations. |
| Incorrectly installed systems can waste water and care must be taken not to contaminate mains water supplies through backflow. |
| If backflow occurs during blood sample aspiration or from a transfusion, there also could be contamination. |
