A liquid treatment device includes a container section (410) defining a container for holding liquid to be treated. The container section (410) includes at least part of a body, the body including at least one wall (412) forming at least a bottom of the container. At least one first liquid-permeable window through the wall (412) forming the bottom of the container is provided. The device also includes a liquid treatment section (411), including a cavity (417) surrounded by a cavity side wall (418) forming at least one second liquid-permeable window for treating liquid passing through it. The cavity side wall (418) is sealingly joined to a liquid-impermeable wall section (435) along the circumference of the cavity side wall (418) and around a liquid path through the cavity (417) and the first liquid-permeable windows at an end of the cavity side wall (418) proximal to the at least one first liquid-permeable windows. The liquid-impermeable wall section (435) is an inseparable part of the body.