It is important to calculate standing water present on a water loss as it will have a direct impact on the structure of the walls if it is not calculated and extracted correctly. Water depth must be monitored to ensure it is falling at the predicted rate and is not creating unequal pressure on both the inside and outside of the walls.
1. Safety First
Water and electricity are a dangerous duo
If you must venture down into a flooded basement, wear waterproof rubber boots.
Avoid touching or using electrical devices (except for a battery-powered flashlight) because this puts you at risk of electrical shock or electrocution.
If the basement's electrical systems come in contact with water, it can lead to shocks or even electrocution.
Always turn off the power before entering a flooded basement and never handle electrical items when standing in water.
2. Calculate the length and width of the area affected
If in a basement, determine if the basement is under the entire footprint of the home.
Speak to the homeowner to help determine this
Measure the outside of the building/ home first in feet to obtain and estimate.
If in a basement with potential Electrical hazards, it is recommended to do the measurement after the water is pumped out.
3. Calculate the depth of water
Measure the depth of the water in feet.
Carefully use a yardstick to place into the water to determine the depth of the water
If in a basement with potential Electrical hazards, you can attempt to do this from the steps if possible, or you may have to estimate the depth.
One way is to visually look and take photos of the walls to mark the level, and then measure it after the water is removed
4. Cubic Feet -Multiply the results from previous steps
Length x width x depth to find cubic feet (cubic meters) of water.
If any of your measurements are in inches, be sure to convert it to feet by dividing by 12.
Example: 4" divided by 12 = 0.3 feet
5. Find how many gallons of water
Multiply cubic feet (from step 4) by 7.48 to find how many gallons of water there is.
If working in cubic meters: Multiply cubic meters by 1,000 to find out how many litres.
Example calculation:
30' x 30' = 900 sq. ft. 900 sq. ft x 5 inches deep (5/12" or .4166) = 375 cu ft. each cubic foot holds 7.48 gallons so 375 x 7.48= 2805 gallons of water.
6. Calculate the weight of the water
Multiply gallons (from step 5) by 8.345 to find the weight of the water.
If working in litres: One liter weighs one kilogram.
7. Danger of Pump Standing Water in a basement
Don't Pump Out Basements Too Early or Too Fast!
Removing all the water at once may cause serious structural damage to the house.
Draining the water too fast could cause the collapse of the cellar walls, floors and foundation. The water must be drained slowly to equalize pressure on both sides of the wall
Although the flood waters have receded, water still in the ground outside your house may be pushing hard against the outside of your basement walls.
The water in the basement is pushing back.
If basements are drained faster than the water on the outside is draining, the outside pressure will be greater than the inside pressure and may cause the foundation, basement walls or floor to crack or rupture.
8. Procedure for pumping water from Basements
It is recommended the following procedures be followed when pumping basements to avoid serious damage, collapse or injury to occupants:
- Begin pumping when floodwaters are no longer covering the ground outside.
- Pump out 1 foot of water. Mark the water level and wait overnight.
- Check the water level the next day. If the level went back up (covered your mark) it is still too early to drain your basement.
- Wait 24 hours, and then pump the water down 1 foot again. Check the level the next day.
- When the water in the basement stops returning to your mark, pump out two to 3 feet and wait overnight.
- Repeat daily until all the water is out of the basement.
