Yes, and particularly you have both the sink and shower going into the same side. Reason for this is that the shower is much lower than the sink, so the water goes to the shower . If the shower is closest to the pump, the problem in greater (and why the installation manual advises to locate a lower waste point (the shower) into the other side. If the basin is closer, install a Hep20 horizontal diaphragm trap between these - or even easier, take the sink waste to the lid spigot. If it enters the top it cannot get out as the side inlets have valves that stop the water exiting. Chris (Australia)
chris olsen, March 2008
