(Reuters) - Portable toilets vendor United Site Services Inc is exploring a sale that could value it at around $4 billion, including debt, as its hand wash stations business sees strong demand during the pandemic, people familiar with the matter said on Friday.

Platinum Equity LLC, the buyout firm which owns United Site Services, has hired investment bankers to advise it on a sale process, the two sources said, requesting anonymity as the matter is confidential.

United Site Services was valued at just $1.15 billion when Platinum Equity acquired the Westborough, Massachusetts-based company four years ago, according to credit ratings agency Moody’s Investors Service Inc. It now has 12-month earnings before interest, taxes, depreciation and amortization of more than $300 million, according to the sources.

Platinum declined to comment. United Site Services did not immediately respond to a request for comment.

The COVID-19 pandemic has accelerated the growth of the hand wash stations industry, with the market seen growing from $919.4 million in 2019 to almost $1.5 billion by 2027, according to research firm ResearchAndMarkets.

Platinum Equity acquired United Site Services in August 2017 from private equity firm Calera Capital. In addition to portable toilets and hand wash stations, the company also rents out temporary fencing, roll-off dumpsters and portable storage.

Moody’s said last month it expected United Site Services to continue to benefit from strong market demand in the sanitation sector, recognize benefits from recent cost actions and acquisitions, and drive margin improvement.

Los Angeles-based Platinum is run by billionaire founder Tom Gores. The firm says it has around $23 billion in assets under management and also owns U.S. basketball team the Detroit Pistons.

Reporting by Joshua Franklin in Miami; Editing by Susan Fenton

Our Standards: The Thomson Reuters Trust Principles.

All quotes delayed a minimum of 15 minutes. See here for a complete list of exchanges and delays.