clean water sanitation resource-based economy Kadagaya

The water infrastructure in most cities today provides a single potable water supply which is used for drinking, bathing, washing clothes and dishes, watering gardens, etc. It is unnecessary and wasteful to be flushing toilets with drinking-quality water and it is more efficient to have several grades of water for different purposes. Three main grades can be classified (1) drinking water: high quality, clean water, with acceptably low levels of pathogens, salt, toxic chemical etc. (2) grey water: household waste water (e.g. from showers, washing clothes and cooking) that does not contain faecal matter, and (3) black water: waste water from toilets etc. that has been in contact with human faecal matter and contains pathogens. Waste water from workshops and laboratories may require additional treatment due to contamination with e.g. heavy metals and industrial chemicals. Thoughtful design of the water network and material that enters the waste stream (e.g. detergents) is important to maximise efficient water use and facilitate recycling and re-use.

The pilot project location (in a tropical region of Peru) has access to water from a nearby river and plenty of rainfall. Rainwater is the cleanest source for drinking and is collected in tanks from the rooves of buildings. In the long term, drinking-quality water will be used for cooking, drinking, and personal hygiene only. For washing clothes, cleaning and agriculture a lower grade of water can be used (e.g. from the river or recycled). Testing and monitoring of the water quality will be undertaken to determine the requirements for purification. Water is collected in storage tanks and then pumped to header tanks for gravity feeding to the buildings. River water can be pumped from the river to the community using a water wheel (powered by the movement of the river).

Grey water will be processed in retention ponds where filtration occurs and the water is cleaned by natural biochemical processes. These ponds will have specially selected plants for cleaning the water and be landscaped to be an attractive feature of the garden and look like a natural part of the environment. It will be evaluated if the bamboo (for construction) can be planted in these ponds as they have high water requirements.

Here we have very high seasonal rainfall and it is important to design suitable drainage and rainwater management to avoid flooding. This is important as dirty water and poor drainage are major disease factors (particularly with respect to mosquito-borne diseases in this area). Human waste from toilets is currently being collected in composting latrines. Within the village design faecal waste will be collected in a bioreactor for producing methane gas (for cooking).