As noted by other entrants, vast quantities of water is wasted as a result of flushing toilets. Not that I recommend not flushing your toilet!

The basic idea is that the much of this water can be saved by replacing it as the carrier medium with a hydrocarbon alternative. The most obvious but not necessarily the best hydrocarbon would be vegetable oil but this would need to be confirmed.

The reasons for replacing the water with oil are the following:
1. Oil and water (in the form of urine) naturally separate. This means the undesireable elements (i.e. urine and faeces) can be easily separated, thereby drastically reducing the volume of material that needs to be pumped to the sewage treatment plant for treatment.

2. Oil, more or less, doesn't evaporate meaning that even if the toilet is not flushed anything left in it should always be covered by a layer of oil, thereby suppressing the smell (among other things).

3. The oil can be engineered such that anti-bacterial additives can be included, potentially virtually eliminating any smells and airbourne diseases associated with faeces, etc. Alternatively, "friendly" bacteria could be included to promote the breakdown of the faeces further reducing the volume of material that needs to be transported.

Thank you for your consideration.