It is a relevant issue, urban runoff is wasted un utilized. Israel has done good work on such issue.

Urban run-off, if treated can be used for various requirements like watering garden, common toilet cleaning and others.

Howdy, A.R.,

It is not only  a good idea. In my country (Belgium) when folks build new houses or appartments or whatever buidling its obligatory by law to:

1. Insulate a newly built  house or any other type of new buidling , so that energy is not wasted during the winter, spring and autumn seasons;

2. Collect all precipiatation, whether as snow, hail or rain from the rooftops into a subsurface reservoir of about at least 5 cubic meters (5000 liters of water). This so-called gray  water MUST obligatorily be used to flush toilets, wash cars, irrigate gardens, clean stone floors, wash clothes,...

3° Last but not least a citizen building a new house is oblighed by law to rpovide electricity for the house using photo-vlotaic solar cells.

People not following these law imposed investmennts lose the buidling and encironemntal permits to build a house or wahetever buidling.

That's what the law imposes in my country with regard to collceting precipitation run-off from roofs of housing, buildings or whatever has a roof.

Mean precipitation level in my country is about 1200 mm, hence we never have water shortages. MOroever, the population has to recycle everything that is reclable. This has led to an almost closed material cycle for many chemicals and products over the last 20 years. The recycling percentage is over 70%.

So, welcome in Belgium. Called a failed state by the English UKIP party. Can you dig that?

surprised about that legislation is going so far. Thank for the up-date.

There is a few hings to consider.

A) urban runoff can be collected and used as Frank has so clearly demonstrated. Several regions in the world have programmes on that.

B) trouble is urban runoff is not very clean. It contains a lot of urban dust (PAHs etc) dependning on the buildings in the catchments they can also contain a lot of biocides used to protect the buildings addtionanally brids droppings need to be considered. So while usage as greywater (for flushing toilets) can generally be reached without too big trouble it will be some way to get the water to drinking water standards. Also use in washing machines might thus be reconsidered for hygienic reasons.

Under urban and periurban agriculture, there are a number of concerns related to environmental and health related-threats, if sewage water is used, and water is contaminated with heavy metals and nitrates, can lead to amoebic dysentery. There is an adverse impact of wastewater irrigation on food safety in peri-urban areas. Pretreatment of water is the solution.

You can get fairly high rates of treatment by using green infrastructure (grassed swales, vegetated buffer strips, infiltration facilities, etc.)  Maintenance is required to keep it working, but it's not much.  When the treatment efficiency drops a little, you go in with the maintenance - maybe 1% to 2% of construction cost annually, with maintenance schedules in the order of once every 3 to 10 years.  Particularly for infiltration basins, you just watch to make sure the water drains away fast enough - if there is ponding the next day, it needs maintenance.

Just found the following study, which maybe relevant

http://www.mdpi.com/2073-4441/8/6/264

Dears

Thank you all for sharing your views. Special thank to Frank and Titus for providing so much information. The average rainfall in Iran is about 250 mm/yr and yet we do not have good laws like the ones in Belgium. The reuse of water whether runoff or the grey water generated within the residential sector can lead to lots of savings. The paper sent by Titus clearly shows the importance and the methods of collection and reuse. I would like to request you all to help me to get access into monitoring systems too. As you know there is monitoring systems for checking air quality in many metropolitan cities. Is there such system developed for runoff waters too?

Truly yours

Instead of the proliferation of multiple individual systems (or additionally?), with all natural problems of operation and lack of knowledge for performing it suitably by the common citizens, perhaps even better could be the construction of detention ponds in the urban areas for collecting the superficial runoff resulting from the precipitation and subsequent drainage in the sewer networks, and perform the control the water quality in the retention basins. The parameters to be controlled are regulated by the international and national norms and probably, depending of the uses considered, some sort of treatment could be required, according to the water quality required in reuse. In this context, separate systems are naturally advisable. Naturally that the reuse of wastewater is more important in areas of scarce water resources. However, individual systems, besides eventual reduction in water consumption in the water supply system, have perhaps the advantage of reducing a little the peak flows in the origin and the overflows of the networks, many of which are still combined and with all problems of pollution associated.

Dear Antonio

Thank you very much for sharing your ideas with me.

Truly yours