Last week I dicussed options for reducing the amount of water that you use inside your house through adapting your habits and installing fixtures or appliances that are more efficient. This week we need to talk about what goes on outside, because a lot of the water that you use never actually enters your house but instead gets used for irrigating landscaping. This water has been processed to make it safe to use for consumption, which is a much bigger investment of energy than needed. There are a number of sustainable water solutions that address not only reducing the amount of water used for irrigation, but also what you can do with water as it comes to your site (in the form of rain) or leaves your house (as greywater). All of these are important considerations in green building.
Plant native landscaping: The most important thing that you can do to reduce water use for landscaping is to put in native or drought resistant plants. If you are lucky enough to live in Austin, the city provides a great searchable database of plants that are suitable to this area, with information on how much shade and water they need, as well as details on when they bloom, how large they get, and what wildlife might be attracted to them (http://austintexas.gov/department/plants). 
If you live elsewhere in Texas or the US, your local nursery should be able to provide you with information about what plants are suitable to your area, or you can find information from the Lady Bird Johnson Wildflower Center on what plants are appropriate to each state at http://www.wildflower.org/collections/. It used to be difficult to find native plants, but they are making a comeback in many nurseries and are sometimes even available now at big chains, if you know what to look for. If you commit to planting only new plants that have low water needs, you can slowly transition your landscaping to use less and less water. Grass is one of the biggest water consumers, so you may want to consider replacing lawns with landscaped areas that have native grasses, mulch, or stone landscaping.
Harvest your own water: Even drought resistant landscaping still needs a little help sometimes, and you may not be able to give up that last piece of grassy lawn, so even if you do change your landscaping you might also consider collecting water to use for irrigation. Rainwater collection systems can range from simple old barrels under the eaves to fancy underground tanks with their own filtration systems. Many new systems are cropping up in response to increased interest in rainwater collection, so you will have a lot of options to choose from. 
If you want to start simple, take a look at your roof and see if there are areas where water is concentrated when it comes off the roof (typically this happens in troughs where two roof pitches come together) and put a rain barrel there that you can use to fill a watering can. If you are interested in taking it a step further, install gutters that direct water into a series of storage tanks. These storage tanks can then be connected to a drip irrigation system for your landscaping, which delivers water directly to plant roots where it is needed rather than putting it on the surface to evaporate. Another great source for water during hotter months is condensate from your air conditioner, which can be collected and used to water plants at the times when they most need it. You can locate the condensate drain in your house and see if there is a way to redirect that water toward areas where it is needed.
Recycle water: The water from showers, sinks, and washers is generally fairly clean and can often be reused with minimal treatment, as long as harsh detergents and cleaners are avoided. Greywater, as it’s called, can be collected, filtered, and used to flush toilets or irrigate landscaping. Installing a private collection and filtration system can be problematic in urban areas with restrictive regulations, but some new neighborhoods in dry areas like Austin and Phoenix are installing greywater collection systems alongside traditional wastewater collection. While this is a step in water conservation that goes beyond what most people are used to, it is likely to become more common and is worth considering, especially in new construction.
If you are building a house, find out what the regulations are regarding greywater in your area, and whether future plans might include developing greywater collection. Consider installing a plumbing system that distinguishes between greywater, which can be treated and reused on-site, and blackwater, which needs to go through a sewage or septic system for treatment. If you are permitted to collect and treat your own greywater, there are a good resources available to help you figure out how to use it, for example http://greywateraction.org/content/about-greywater-reuse. Most greywater can be used directly to irrigate landscaping, but if you generate more than is needed for this or want to reuse the water for other things, you could install a constructed wetland treatment system that also functions as a landscape feature, since certain kinds of plants are particularly good at filtering water and removing the phosphates from detergents.