This technique is suitable for any floor that has either a drain or an open side where water can spill onto the ground. I learned the cleaning technique at Girl Scout camp, and years later I realized its wonderful compatibility with those “still very soapy on the inside but with not enough soap to pour” bottles. It’s thrifty, it’s fun, it’s safe for kids to help with, it’s good exercise, and it gets the floor really clean, so it works for me!
When your laundry detergent bottle reaches that almost-used-up stage, put the cap on the bottle and set it aside until you need to wash the floor. If your floor drains onto the ground so that the water will be watering your plants (very efficient!) it’s important to use environmentally friendly detergent–see recommendations in my laundry article. One big detergent jug will clean at least 100 square feet of moderately dirty floor. Save up 2 or 3 jugs to clean a big or filthy floor.
The only other thing you need is a broom that can get wet. If you have one of those wide push-brooms, those are especially good for cleaning and rinsing the big areas of the floor, but you’ll want a regular broom to scrub into the corners.
Ideally, you’ll do this barefoot. If it’s too cold or there’s a possibility of broken glass on your floor (when we cleaned our basement last Saturday, we knew that contractors had broken a light bulb in there, and we weren’t sure if we’d found all the pieces) or for some other reason you have to wear shoes, you’ll want to wash the soles of your shoes after the first round of washing the floor so that you don’t make muddy footprints.
Sweep up loose dust and debris. However, if you have asthma or dust allergies, you can reduce irritation by skipping this step and wetting down the dust right away–you’re just going to have to do more rounds of washing to remove all of it.
Fill the detergent bottle 3/4 full with hot water. Put on the cap. Shake. Slosh the soapy water on the highest part of the floor. Now sweep! Sweep like crazy! Sweep it all around! Use the broom like a long-handled scrub-brush to loosen gunk. Work your way down the slope, finally sweeping the dirty water down the drain/off the edge of the porch. Rinse your broom.
Repeat the above step until the whole floor is clean and the water is coming out less soapy–in my experience, these tend to happen at about the same time because there’s always more soap left in the bottle than I think there could possibly be!
If you happen to have a bucket handy, it’s better for rinsing than the empty bottle because it will not have any traces of soap in it. Pour plain hot water all over the floor, sweep it around with your rinsed broom, and sweep it down the drain/off the edge. Repeat if necessary.
The drainage can be tricky if your floor has weird low spots; it’s hard to sweep the puddles out of them. Another option is to suck up the puddles with a wet/dry vacuum cleaner . . . but then you have to clean out the vac, so I think it’s usually easier to sweep water uphill.
This is the end of the instructions; stay tuned if you want to read an anecdote of extreme use of this technique: The one time I was very glad to have the ShopVac was when I cleaned the basement floor in the laundry area of one apartment building where we lived. (This was when I thought of using dregs of laundry detergent–there was a large cabinet in the basement filled with almost-empty detergent bottles stashed by previous tenants!) I poured soapy water on the grayish-tan concrete floor and started sweeping, and there were these disturbing red streaks I couldn’t figure out–was there some kind of red stuff lurking in those old bottles? After more sweeping, I realized that the floor actually was painted red!! It had been so solidly filthy that none of its true surface was visible! Closer inspection revealed that the floor was covered in a thick layer of grayish-tan stuff (probably a combination of laundry lint, mud, and random dust) and under that a layer of coal dust. Now, coal furnaces were very popular in Pittsburgh, so I was not at all surprised that the building had once had one, but pretty much everybody replaced their coal furnaces with natural gas ones by about 1970 . . . so this basement floor had not been cleaned for thirty years! And I admit that I never did clean the whole thing, partly because of the amount of heavy junk in the rest of the basement (the landlord refused to arrange disposal of our old water heater after it exploded and we got a new one, and there was evidence that he had done this 7 previous times, etc.) and partly because cleaning the laundry area was such an ordeal. It took me 4 hours to dissolve all that filth into mud and suck up the mud with the ShopVac, and I was only cleaning the area under the clotheslines, about 6’x20′ . . . and I later learned that, whenever there was a heavy rain, gritty mud would flow across the basement floor (I never figured out exactly where it was coming from) so that the floor had to be cleaned again! I’m thrilled that we lived there for only two years before buying a house with a dry, relatively clean basement.