2.5 gallons is plenty of water for an extract batch with steeping grains. Even topping up to 5 gallons.
Plenty of great beers made that way. That was where myself and probably a lot of us started.
Just need to find a recipe and have it scaled to 4 gallons most online kits and recipes are for 5 or more gallons. You can roughly do 4/5 of all extract grains and hops to scale it down from a 5 gallon recipe
Primary1: Empty, Primary2: Empty,Primary3: SWMBO WIT, Primary4: Empty
Bottled: Porter, Blonde, Stoutly, Rasberry WIT, Kitchen Sink IPA Kegged:Feeding Frenzy IPA, SWMBO WIT
On tap: Black Tip Stout, Hopperhead IPA Up next The Blonde that went to India.