Under Pressure: The Secret Culprit of Basement Flooding

It’s Friday afternoon which is a great time for learning about hydrostatic pressure.

You may not think you know what hydrostatic pressure is, but if you’ve ever had water come up through your basement floor, you’ve seen it in action.

Hydrostatic pressure is a fancy term for water pressure, and to understand what it is and why it’s a problem, you have to think of a few things: digging a hole at the beach, and watering a plant.

First, the hole. When you dig in the sand in an attempt to bury something or someone, there’s always that moment where you hit wet sand, and then you dig one more time and see an actual pool of water. That’s the water table, and its depth is determined by a few factors, including distance from a body of water and recent rainfall. If you live close to a lake, for instance, your water table will be higher than if you’re pretty landlocked. And if it’s been raining a lot lately, the water table will rise as the soil absorbs the moisture.

Which brings us to our next point. When you overwater a plant, there’s a point where the soil just can’t absorb anymore water and the excess goes wherever it can - overflows over the top of the pot, streams through the holes in the bottom - which is exactly what the dirt outside does. Only your basement is the pot.

Water weighs a little over 60lbs/cubic foot, so when you’re in an area with a high water table, there’s already a lot of pressure in the soil surrounding your house. And pressure’s main goal is to relieve itself, which in this case it will do by finding any avenue to move - likely into your basement. Even the most perfectly constructed foundation may have hairline cracks or just a porosity that leads to water breaking through and ending up in your basement.

That’s the effect of hydrostatic pressure.

So what do you do?

Exterior drain options are often poor solutions, because they become clogged quickly with dirt and roots. It’s like relying on your gutters but not having access to clean them. The best bet here is an interior drain like our WaterGuard below-floor drain system. WaterGuard allows water to flow directly into the system rather than gathering on the floor, and routes the water to a sump pump to be discharged a healthy distance from the house, rather than into the immediate surrounding soil.

So if water is appearing from seemingly nowhere, call us. Your house may be under pressure, but it doesn’t have to be underwater.