The Washington Suburban & Sanitation Commission (WSSC) explains Front Foot Benefit Charges;  https://www.wsscwater.com/customer-service/rates/front-foot-benefit-charges.html

Here in Montgomery County we have seen this more and more on the newer developments. It’s a way of prorating service charges specifically to those who are using them.  Instead of the previous method where it’s all pulled from our property taxes, regardless.  If handled properly, this should be a more efficient model.

If you are selling your home and currently pay this yearly FFBC…
You must disclose to your potential Buyers.  It will be listed on your Property taxes as a separate charge from WSSC.
Your Buyers will want to know how much, AND, how long into the future will they owe this.

I’ve been told they typically run 23 years.  It’s on the property, and the length of time does not restart with a new owner.  To find out exactly how much and how long regarding your property, go here;
https://my.wsscwater.com/FFBenefitCharges/benefits/charges/ffbenefitsCharges.faces

Your results will look like this–