Water is the serious question for any desert project

Every project in the semi-desert stands or falls on water. It is the topic that appears least in brochures and the first that should appear in an honest conversation.

How groundwater works in Mexico

In Mexico, water is national property. It is not bought: it is concessioned. The authority is the National Water Commission, CONAGUA, which grants concession titles for a specified annual volume and records them in the Public Registry of Water Rights.

This has a direct consequence: owning the land does not make you the owner of the water beneath it. Drilling a well without a concession is illegal, and concessions are not issued freely.

CONAGUA publishes availability for each aquifer. When an aquifer is in deficit, a moratorium is declared or new titles are restricted. Across much of northern Mexico, that is the situation.

The question to ask

If you are offered land in an arid zone, one question organizes all the others:

What is the concession title supplying this property, whose name is it in, and what annual volume does it cover?

Acceptable answers are concrete: a title number, a holder and a volume. Unacceptable answers sound like "there is plenty of water here," "it will be applied for," or "the neighbor has a well."

If the development is a condominium, also ask how the right of use transfers to owners and who pays to maintain the water infrastructure.

How much water is actually used

Scale helps. In a home, consumption breaks down quite differently from what intuition suggests: in arid regions, garden irrigation is usually the largest consumer, exceeding all indoor uses combined.

That means the highest-impact decision about a desert home's consumption is not the shower or the toilet. It is what gets planted outside.

A lawn in an arid climate can multiply a household's consumption. A garden of native vegetation can effectively eliminate it after the first years, once the plants are established.

What actually works

Native vegetation. Creosote, mesquite, agaves, cacti. They are adapted to local rainfall and, once established, need no irrigation.

Rainwater capture. It rains little in the desert but it rains concentrated. A modest roof area can capture a surprising volume in a single storm, if there is somewhere to store it.

Greywater reuse. Water from showers and sinks, with simple treatment, serves for irrigation. It requires separate plumbing, so it has to be decided during design, not after.

Drip irrigation on a schedule. Watering at night or at dawn dramatically reduces evaporative loss.

Metering. What is not measured is not managed. A meter per connection changes behavior more than any campaign.

What to demand of a development

A serious project in an arid zone should be able to show you, without discomfort:

• The current concession title and its volume.
• The hydrogeological study of the property.
• The balance between concessioned volume and projected demand at full occupancy.
• The landscaping rules in the internal regulations.
• The wastewater treatment and disposal plan.

If that documentation does not exist or is not shown to you, you already have your answer. In the desert, water is not a technical detail to be resolved later: it is the condition that determines whether the project is viable at all.