There is no such thing as waste. But for the purposes of this, 'waste' is what we produce or generate that require treatment or processing before being used again. 'Treatment or processing' closes the loop of our interaction with materials and in the long term, processes for dealing with waste need to be integrated into our house designs and inform our behaviour. There are some lovely terms to define our liquid and solid waste: blackwater is liquid waste containing urine and faeces, not to be confused with greywater (the liquid waste from baths, sinks, washing machines etc) which is treated very differently. Then there's organic waste - anything that can rot and lastly non-organic waste - that which won't rot, e.g. plastic, glass and metal.