I’m having a humidity problem . This is in my own home. I have a “ whole house humidifier “ on each floor and it’s still only about 25% humidity in here. Each floor is going through 5 gallons of waters in the humidifier. The heat is baseboard hot water. The temperature is between 65-68. The hardwood is suffering as well as my skin. On rainy days, I do open the windows to help, but not many rainy days lately. At this point, I’m thinking of installing a koi pond with waterfall in the living room?

You may be causing your own problems by pumping water into the air thru your "whole house humidifier"! I'm not sure.

But I had a friend with a similar problem that caused mold to grow on the walls. He didn't want to pay for any tests or do any preventive measures.

So I took my air flow meter used to measure air speed and volume traveling through duct works to balance out a central system. I measured the air coming into the house, attic and crawl space under the home. I also measured his a/c central system return vs the vents.

He had too many leaks to count. Leaking air everywhere. The cold from under the house and in the attic got sucked into his central heating system. When cold hits hot, condensations forms making the moist walls with the room heat promote mold growth.

Since this is your home, I'd have an expert do some testing. I also purchased a stiff supply of bags the pull the moisture out of the air. I put them in the closets that kept on growing mold. The bags filled up with water and there was no mold on the walls. Therefore, there was too much moisture in the air.

Rents Due, in our area during the winter months the indoor humidity level should ideally be 40-50% so your home at 25% is way too dry. As you probably already know cold air does not hold moisture like warm air does. I've found that around here that homes especially those with FHW heat generally have low humidity because they are not very well sealed & have a lot of air leaks. I bet that a good deal of your humidifier's 10 gallon per day of water is either escaping to the exterior or condensing on cold surfaces.

Is this an older building?

Do the windows have insulated glass with storm windows?

Does condensation show up on the window / door glass?

How much & what kind of insulation is there in the floors, the walls & the attic?

Are there any vapor barriers?

Are the walls plaster or SR?

Do you use oil or latex paint?

Is there a full basement, a crawl space or a slab?

Do you have a gas stove, fireplace or clothes dryer?

Have you checked the humidity level in each room of the house including the attic, basement & attached garage?

I would look in to having an energy audit done by someone who uses infrared cameras & a blower door. This should help pinpoint any air leaks & give a base line for air changes per hour. Once any air leaks are found & sealed a follow-up blower test should let you know how successful the sealing was.

I'm thinking similar to Steve.

The moist air may be escaping outside.

diagnostics of your problem is impossible without more data

Many questions above need to be answered

How long have you lived there and is this the 1st year his problem has occurred.

I have experts at my fingertips - but can't answer your question without more data

I am sure you have access - FREE - to an energy audit - through your utility

Are you natural gas - call them

If you are oil - call your state energy dept