A pressure fluid reservoir for a traction-controlled vehicle brake system; a reservoir unit including a plurality of pressure fluid reservoirs; and a method for producing a pressure fluid reservoir are disclosed. The pressure fluid reservoir with its structural size unchanged, has a larger installation space for a restoring element cooperating with a reservoir piston and at the same time can be produced economically. To that end, as the reservoir piston, a component reshaped in non-metal-cutting fashion from a sheet-metal material is proposed, on whose circumference an encompassing receptacle for a piston seal is integrally formed, likewise in non-metal-cutting fashion. The reservoir piston can be produced by deep drawing; the receptacle for the piston seal can be produced by roller-burnishing. Both method steps can be performed economically in one combined operation.