a fluid reservoir for a motor vehicle hydraulic brake system , having a housing with at least one fluid chamber , the housing preferably having a housing upper part and a housing lower part , a reservoir warning device for monitoring the reservoir filling level of the fluid reservoir , a filler neck for filling the fluid reservoir , a cap for fluid - tight closure of the filler neck , provisions for pressure balancing of the fluid reservoir and preferably a canister - shaped filling filter arranged in the area of the filler neck and having a wall and a base . in order to provide a cost - effective and easily assembled fluid reservoir , the filling filter , which reliably prevents the ingress of dirt , extends into the fluid chamber and includes a wall molded onto the housing of the fluid reservoir that adjoins the reservoir filler neck .