(Boulder County Colo.—Zero plus 12 days) After you can gain safe re-entry to a salvageable building damaged in a flood disaster, the first step is to evacuate the water and remove the soggy debris. Exposure to toxic chemicals and sewage in standing floodwaters is bad enough, but the lasting danger to a house and its occupants are the pernicious effects of mold for years to come. Mold can set in quickly and is difficult to remove once established. And it needs to be taken very seriously: Besides causing allergic reactions and other respiratory ailments, mold can also wreak havoc on a home's property value.

Floor Drains

First, check that any basement floor drains are free of obstructions so they are able to drain when the sewer (or septic system) level allows. Wearing rubber gloves, take off the drain grate and dig around for mud, rags, lint, or other materials that may be creating a blockage. Chances are the sewer or septic outlet that the drain flows to was also flooded and may have even backflowed into the basement. But as it drains, so should the floor drain. It is important to check the floor drain first: You wouldn't want to discover that a day of pumping could have been avoided simply by removing a plastic grocery bag from the drain grate.

Sump Pits

If the house you are working in has a sump pit, the existing pump might have failed during a power outage or may have just blown its breaker. Proceed with due caution, but see if the installed pump works first. If not, at least the pit will provide the best place for you to pump from.

If you are working in a crawlspace, create a place to pump from by digging a pit several inches deep at the lowest point of the grade.


For pumping out a flooded structure, a trash pump (the polite name for a sewage pump) is the best option for removing a lot of water in a hurry. A large gas engine unit can work without electrical power and, unlike common sump pumps, can handle mud, sludge, and solids with ease. A friend I talked to related how a small rock sucked into his crawlspace sump pump stopped it dead. If he hadn't crawled through the water to clean it out, it would've meant a devastated ground floor rather than just puddles in his crawlspace. (He was also lucky that the power stayed on in his neighborhood).

So if you are renting a pump, a trash pump is preferable. However, during a disaster you may be stuck using whatever type of pump you can get your hands on. By the second full day of rain in Boulder, the rental yards were cleaned out and area stores had sold out of pumps of all sorts. Our large local hardware store handed out numbers and set up dozens of chairs where anxious property owners waited all day for the next shipment of sump pumps that could be rushed in. And the resident big box store responded in a big way to the surge in demand. A store manager told me that they sold all the extra stock they brought in—5,000 sump pumps, 50 gas engine trash pumps, (and 5,000 fans) —in just a few days.

If you use a sump pump, create an external intake filter by setting it inside a 5-gallon bucket with lots of small holes drilled in it; even better, wrap the pump in a piece of screen or hardware cloth. I prefer the screen method because I can get the pump lower to the floor or even set it down into the floor drain opening at the lowest spot in the floor. These rudimentary filters may still need debris pulled away from them when clogged, but they will keep the pump's impeller clear and free from damage.

Remember, you are fighting gravity and friction while pumping, so use the fattest and shortest hose you can, avoid sharp bends and kinks in the hose, and don't lift the water any higher than you have to. Be sure to situate the outlet end of the hose well downhill of the building. Water pumped out into the yard may find its way through the saturated soil and end up back in the basement or crawlspace again.

Many portable submersible sump pumps cycle on and off via a pressure switch, so they won't turn on until they are under several inches of water. This can be a problem once the water level goes down. I can sometimes activate mine by bumping the pump against the floor, but at some point it will stop with a few inches of water left standing. 

Sump pumps with float switches are easier to rig manually because the external floats can be wired or taped into an "on" position, but be careful not to burn out the pump by running it dry. You may get down to as little as one inch of water with one of these pumps.

Regardless of the type of pump you use, you will be left with lots of water still on the floor. So for the next step, you can either bail the remaining water into a bucket with the pump in it, or switch to a wet vac.

Wet Vacs

Wet vacs are very efficient for sucking up water and sludge, and the bigger the vac, the better. I leave all of my European skinny-hose vacs in the shop when it comes to this kind of work and rely on a big, inexpensive vac with a large diameter hose. It works fast, holds a lot of water, and the filter is relatively cheap to replace after extra dirty jobs like this. I know these vacs can be used with the filter off for wet use, but I prefer to leave it on to protect the motor from excess moisture and nasty contaminants.

For efficient wet vacuuming, use the shortest hose you have and avoid loops or low spots in the hose that will act as a trap. Prop a flat nozzle about 1/4-inch off the floor in a corner or at the lowest spot in the floor, and use a large push broom like a floor squeegee to direct the remaining water to the vac.

My vac has a float ball to block off the suction when the vac is full of liquid and you can tell when the ball seals because the motor sound changes to a high-pitched whine. Some of my fancier vacs shut of via an electric circuit that the water closes. Just be sure you know when your vac is full of water so you don't have to wait for a loud pop, a puff of smoke, and all the lights going out to find out.

With my 16-gallon vac full of water, it weighs about 150 pounds so the easy way to empty it is to drop a pump into the tank for several seconds. On jobs without a pump present, fill the tank only partway and empty it into two five gallon buckets that you can carry up the stairs. When clearing a flooded crawlspace, I left the vacuum on the main floor above, rolled it to the doorway when full, and drained it into bucket through the vac's drain port.

Be sure to dump the water outdoors, downhill of the house. Dumping the water into the toilet may result in water rising back up the basement floor drain.

Wet Cleaning

Once the standing flood water has all been sucked up, and you are reasonably sure that the floor drain is not backing up, take advantage of the fact that you have the wet vac system all set up and do any wet cleaning you need to do for the walls and floor surfaces. While everything is still wet, this is your best opportunity to saturate everything with a cleaning product and then provide a good rinse or two with fresh water. The homeowner or their insurance company may require you to use a high-tech anti-mold product, but if not, the old standby is bleach. Lots of bleach.

Mix it 50/50 with water in a large spray bottle and spray down any surface that was wet with flood water. Wood framing, soil pipes, concrete walls and floors—just go easy around the furnace and hot water heater since chlorine is basically liquid rust on steel and iron.

Once every square inch of the affected area is glistening with the bleach solution, give it a little while to soak in and then start rinsing everything from the walls down with fresh water. As before, squeegee the water with a push broom and collect it with the wet vac. 

If you have an asphalt-patching or floor squeegee, they work well to rub the floor dry. If not, put a wide nozzle on the shop vac and go over the entire floor slowly to begin the drying process.

Caution! Chlorine bleach and other disinfecting cleaners are toxic to living things—not just to the microbes and spores you are attacking, but to you as well —so be sure to wear an effective respirator and goggles. Avoid direct contact with skin, and provide fresh air while applying any chemicals.

The next few reports will include my visit to a Habitat for Humanity flood-relief job site, recommendations for successfully drying out a building, and requirements of contractors that have been amended and even suspended by local and national building officials during this state of disaster.

This is the second in a series of reports intended to help inform both the victims of natural disasters as well as the contractors they look to in these times of crisis.