Cisco Holland, a manager at Servpro, a flood cleanup company, rushed to Milton Thursday morning to answer a homeowner’s call for help. His basement had been submerged in water for several days, and because mold can form within 72 hours of flooding, a messy problem was becoming a crisis.

“Time is of the essence,’’ Holland said as he readied to go inspect the damage.

Time is also money for cleanup specialists, who have been in high demand in Massachusetts in recent weeks, and whose ranks appear to be increasing nationwide. From