Lingo >Sneft Hole

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If you look at a dip tube, up high on the side is a tiny hole (circled in red in the photo). It's not there by accident. It's called a sneft hole and is an anti-siphon precaution. If there were to be a break in the water main, without the hole, all the water in the tank would siphon out and then the tank would explode.