By 2030, it is estimated that global demand for usable water will exceed supply by about 40% - unless there are radical changes in water consumption and new technological advances. The situation in India is arguably even more severe, as the following panel shows (from “Charting Our Water Future,” 2030 Water Resources Group, 2009).

Your task is to design a new building complex in an Indian city or rural area that incorporates the state-of-the-art water technologies needed to meet this impending crisis and is commercially feasible at the same time.

The building complex can be assumed to consist of 5 high-rise buildings accommodating 10 apartments each. Each household in an apartment operates independently but is able to access common resources and shared services within each building as well within the complex. You may assume that not more than 20% of the total land area in the building complex can be used for such common resources and shared services.

Your design, at the least, should have the following features enabled:

Water harvesting: Harvesting and collection of rainwater and other naturally occurring sources of water is becoming obligatory in several communities. How is this best done, particularly in places with seasonal weather patterns?

Water purification: There are a range of water purification methods, including tried and tested ones such as various forms of filtration and reverse osmosis. What are most promising technologies for domestic use, keeping in mind the varied needs households have for water?

Water reuse: Recycling of water is an ancient practice that is again vital. Modern communities require water of differing quality for differing needs. What are the implications of this for creating a ‘service model’ for water reuse, where recycled water can be a shared resource?

Water metering: Like electrical power, water is a valuable commodity that communities can be expected to pay for. Are there technologies (advanced sensors, for example) that make it possible to devise accurate usage and metering systems?

Water discharge: Environmental and other considerations increasingly require that wastewater be treated before discharging into the ground. How can this be done economically, keeping in mind possible integrations with water storage?

Engineering considerations

The building that you design should be consistent with current state-of-the-art in structural and power engineering as well. You are free to innovate in these areas too, so long as they advance the basic water objectives. However, do justify any new science or engineering you are proposing with relevant supporting data or research. (For instance, are there better ways to design storage tanks and water pipes than what is being used today?)

A. How much physical space do you require to deploy your solutions and innovations? The less the space requirement, the easier it might be to adapt to existing designs.

B. How much energy is required to operate the technology you are proposing? This can be thought as total electrical power or in terms of power per unit volume of water treated. Lower energy requirements and greater energy efficiency are likely to make your design more affordable (see below). Limiting the additional energy required to within 10% of the normal energy consumption of a household can make your design particularly attractive.

Financial considerations

It is important that you remember that households have financial constraints and that cost considerations are therefore crucial. Your solutions should preferably be at the lowest possible cost and require the least amount of maintenance (remember aspects such as corrosion). More sophisticated alternatives are also welcome – economic and environmental circumstances vary across communities.

A. What is the capital expenditure required? In other words, how much do your proposed water technologies add to the cost of constructing the complex?

B. What is the operating expenditure required? In other words, how much needs to be paid per year/month by residents for continual use of your proposed water technologies? If this amount is more than 5% of the average monthly budget of the consumer, then the solution may become less practical.

It is suggested that you at least carry out the following fact-finding exercises:

1. Visit houses or apartment complexes near your college. Try to find out how much water is consumed and for purposes, i.e. do ‘water audits.’ Note that this is not likely to be constant over days or months, so multiple visits or data collections may be required.

2. Understand what is meant by ‘white water,’ ‘grey water’ and ‘black water’ in various water use cases and reuse scenarios.

3. Gather information on the quality of water that is available to the residents. This may require taking samples and getting analytical results on water hardness or particulate contamination. Follow-up discussions might include water treatment methods currently in use.

4. Obtain data (or interact with the appropriate officials) relating to how much water is provided by your local municipality, corporation, or other governing body. If there is a supply-demand gap, investigate what other sources of water households have.

5. Innovations in clean water technology are regularly announced. Do a survey from sources such as the United Nations, the Government of India, various patent databases, and publications from universities to get updated on recent advances.

In addition to describing the background research and technology solution that you are proposing, you are strongly advised to also:

A. Devise, build, and experimentally demonstrate any technologies you propose, even if they are on a smaller scale than for use in a building. Alternatively, computer simulation studies can also be a good way to show the validity and utility of your approach.

B. Carry out a comprehensive commercial feasibility study detailing the cost of your solution as compared to the benefits. The financial estimates that you use should be based on current prices, but also be consistent with future expectations.

Do remember that your customer is the house of the future and its residents. Convince them that you have the solution to one of their toughest problems – easily available, clean, safe, and affordable water!