If you are worried about water contamination then these valves are essential. Some times referred to as check valves. So what applications would they be used in. If you would like one here is the link from my Amazon shop.
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Saved money on plumbers coming out? Want to donate and keep our spirits up? Here is the link. [ Ссылка ]
Many thanks Al and Jan.
![](https://s2.save4k.ru/pic/L17PjOmc8AI/maxresdefault.jpg)