I have an old house with an uneven concrete floor that occasionally needs to be cleaned. The basement floods during a hard rain due to some landscaping issues that I'm working on. I've cleaned it with a scrub brush and mop, but that can take quite a while and many passes before it's fully cleaned. I could also use a pressure washer but the spray from it might get other parts of my basement wet. I've looked at some concrete floor cleaning machines but they all seem designed for flat, smooth floors. What's the best way to easily clean the floor?
Mopping is great. It shouldn't be that dirty subsequent times, so it won't take as long from here out. Sweeping or vacuuming before mopping will help reduce the chance of needing more than one pass.
If you want a less manual mopping, you can get a mopping floor machine, steam floor machine, or a robotic mopper (like a roomba). Or you can get a big yellow rubbermade janitor-level mop and bucket for about $75 that will make mopping a lot quicker.
Adding a floor treatment like epoxy would also help reduce the permeability and increase the smoothness of the floor, which makes sweeping and mopping more effective. You can also just get cheap indoor/outdoor carpet for the flattest parts to cut down on what need scrubbed and mopped.
You already found it, nobody said it would be easy.
If you have a functioning sump you might be able to use a normal hose rather than a pressure washer to move most of the loosened-by-the-brush dirt out to the sump before a final mopping up. If you don't have a sump, either keep doing what you are doing or look into leveling it. One approach to leveling and easier to clean would be to set tiles in a thick mortar bed (or over a self leveling product, using thinset) that eases most of the bumps.
Another, possibly helpful, approach would be a wet/dry shop vacuum.
A light acid etch will make cleaning easier 1-2% muriatic and water, prior to epoxy coating a small garage I used to etch the floor every year after we cut up our deer and elk I think I had done that in this garage 10+ years and it did not damage the concrete, if a stronger solution was used the acid could over etch.
It sounds like you don’t have drainage so a shop vac will be needed to suck up the excess water. After I finally epoxy coated that floor the next year the mess from cutting up several animals cleaned up with a mild soap and water.
You might consider a floor paint to make the cleanup easier I mentioned paint because it will be 1/3 the cost of epoxy but still seal and make cleanup easier.
I usually do this with a water vacuum:
It's like a normal vacuum cleaner, except there is no filter bag inside, and it can suck water without damaging the motor. Also quite convenient to clean large quantity of sawdust, demolition dust, mud, sand, etc.
In your case the important features are that
It will suck mud out of an irregular surface like concrete. If some remains, just add more water, go at it with a scrub brush to un-stick the mud off the floor and mix it with the water, and suck it out. It will remove most of the water so it dries quickly afterward. It will also suck sand and small pebbles.
For this to work well you need the "head" of the vacuum (blue arrow) to be specially designed to suck water, a normal attachment for carpets will not work. So make sure to check when you buy it: it should have two rubber scrapers on both sides to create a good vacuum against your irregular floor.