Mold present in sump pump bucket
Mold grows in warm, moist places and a commonly warm and moist place is the sump pump bucket in your crawlspace. If your sump pump isn't removing water intrusion completely, then you'll end up with a bad situation like this.
Overview of Moldy Crawlspace
Shockingly, this crawlspace doesn't look so bad in overview. It's not until you start really examining the little things that you notice mold growth. Your crawlspace could be doing the same thing--hiding mold problems in plain sight.
Mold Growing on wooden subfloor beams
Here, you can see that mold is growing on the subfloor beams in the crawlspace. It's common to find mold here because it requires organic material to feed on, as well as moisture and warmth. Wood is an excellent place for mold to flourish.
Overview of plumbing and mold
Another place that it's common to find mold is on the plumbing and HVAC systems. Pipes like these often sweat, leaving a moisture coating that attracts mold spores.
Moldy Insulation
Here's the picture that will really make your skin crawl. Many dirt crawlspaces are chilly places in the colder months and it's common to see fiberglass insulation present to warm up the floors in the living areas. Unfortunately, fiberglass insulation is extremely susceptible to mold and that creates a huge health hazard.