Abstract: A device for introducing liquid additive into water flowing through a feed pipe of a domestic shower, wherein the device has a short length of pipe which is connected in the feed pipe, and is provided with means whereby some of the water flowing through the short pipe is deflected into a mixing chamber, wherein it mixes with the additive, and the mixture is fed back into the short length of pipe to join the main stream of water. The water is deflected into said cavity downstream of where the mixture returns to the interior of the short pipe, so that there is sufficient delay in the return of the water to the mainstream to effect mixing of the additive with the water in said chamber.