Amounts of Water Generated by Household Activity

Source:  InterNACHI "Air Quality For Inspectors Course"

Many seemingly innocent sources create significant water vapor in homes. Note from the table that building materials emit 40 quarts per day of moisture into a home the first year after the home is built. An unvented gas range contributes more to indoor moisture load than showering and bathing.
Try to create a list of common household moisture sources, and then rank them for importance. Take into consideration the following list of moisture sources:

• Running an unvented kerosene or gas fired space heater — each gallon of fuel burned creates about 7.5 pints of water vapor.
• Cooking a gas range without using a ducted range hood — each burner produces between 1 and 2 pints per hour.
• Storing firewood indoors — a cord of green firewood creates about 3.5 pints of water per day.
• Air drying clothes inside — each load of wash creates about 5 pints of water during drying.
• Showering — a 10-minute shower creates about 1 pint of water.
• Cooking without pot lids — about 1/6 pint per person per meal.
• Washing floors — about 4 pints per room.
• Watering plants — all the water is poured into house plants eventually evaporates into the room.
• Pets — pets, and people, create about 1 pint of water per 50 lbs of body weight per day.
• Hand washing dishes, including rinsing — about 1/3 pint per person per meal.
• Faucet aerators — 0.02 pints per minute.

Common Household Moisture Sources Moisture source  Estimated amount (pints)
Bathing

• tub (excludes towels and spillage)0.12/standard size bath
• shower (excludes towels and spillage) 0.52/5-minute shower

Clothes washing (automatic, lid closed, standpipe discharge)  0+/load (usually nil)
Clothes drying

• vented outdoors 0+/load (usually nil)not vented outdoors, or
• indoor line drying 4.68 to 6.18/load (more if gas dryer)

Combustion (unvented kerosene space heater) 7.6/gallon of kerosene burned

Cooking

• breakfast (family of four, average) 0.35 (plus 0.58 if cooking with gas)
• lunch (family of four, average) 0.53 (plus 0.68 if cooking with gas)
• dinner (family of four, average) 1.22 (plus 1.58 if cooking with gas)
• simmer at 203°F, 10 minutes, 6-inch pan less than 0.01 if covered, 0.13 if uncovered
• boil 10 minutes, 6-inch pan 0.48 if covered, 0.57 if uncovered

Dishwashing

• breakfast (family of four, average) 0.21
• lunch (family of four, average) 0.16
• dinner (family of four, average) 0.68

Firewood storage indoors (cord of green firewood) 400 to 800/6 months

Floor mopping 0.03/square foot

Gas range pilot light (each) 0.37 or less/day

House plants (five to seven average plants) 0.86 to 0.96/day

Humidifiers 0 to 120+/day (2.08 average/hour)

Respiration and perspiration (family of four, average) 0.44/hour (family of four, average)

Refrigerator defrost 1 .03/day (average)

Saunas, steambaths, and whirlpools 0 to 2.7+/hour

Combustion exhaust gas backdrafting or spillage 0 to 6,720+/year

Evaporation from building materials seasonal 6.33 to 16.91/average day
new construction 10+/average day

Ground moisture migration 0 to 105/day

​Seasonal high outdoor humidity 64 to 249+/day