The pumps are not dependable. Even before covid there were many missing their handles or not working. Also the water is treated with iodine. Imo it taste awful. Depending on your daily miliage you can easily get to towns once or twice a day. Here is a list of towns that have at least a convenience store. I will put the miliage mark in front and this is starting at the D.C. end. Corresponding to the markers on the canal.
Mm 15 great falls visitor center snacks water
mm 48 Point of Rocks. Convienence store/deli
mm 55 Brunswick bike shop resturants small grocery store
Mm 75 sheperdstown convenience store +lots more but spread out
mm 100 williamsport convenience store resturant small grocery
Mm 126 Hancock bike shop grocery restaurants stores
157 Pawpaw small grocery and convenience store
184 cumberland large town.
this is from memory and a few journals these are the towns and places I'm most familiar with miliage is not 100% accurate. Also these are small towns and a lot of the places have limited hours.
I did not include Harpers Ferry. The pedestrian bridge is still closed to the best of my knowledge.
Another thing Dominoes pizza delivers to Swains lock mm18.
a filter is convenient but not imperative. You could just plan on town stops and carry water purification tablets or a couple ounces of clorox for emergencies. Google treating water with clorox.