# How Is Water Managed on a Desert Development in Coahuila?

Groundwater is concessioned, not bought with the land. What CONAGUA reports on the Paredón aquifer, and what to ask before buying in arid land.

By the Grupo Server editorial team · [Editorial policy](https://gruposerver.com.mx/en/blog/editorial/)

Published September 9, 2026

In the Coahuila desert, water does not come with the deed to the land: it is concessioned separately, and around Paredón that concession is already stretched thin. The Paredón aquifer (key 0508) has no volume available for new concessions — its deficit runs to 39,033,049 cubic meters a year, according to the water-availability update Mexico's National Water Commission (CONAGUA) published in 2024 \[2\]. Before talking about land in this area, you have to talk about water.

**Key facts**

- National water is exploited only under a concession granted by the Federal Executive through CONAGUA; owning the land gives no right to the water beneath it (Ley de Aguas Nacionales, art. 20) \[1\].
- The Paredón aquifer, key 0508, covers 6,291 km², mostly within the municipality of Ramos Arizpe (CONAGUA, 2024) \[2\].
- The Paredón aquifer receives average annual recharge of 23.6 hm³ against 59,333,049 m³ of licensed extraction recorded in REPDA (today the REPNA) as of 30 December 2022, according to CONAGUA \[2\].
- Since the decree published in Mexico's Federal Official Gazette on 5 April 2013, no well may be drilled in the Paredón aquifer without a CONAGUA concession \[2\].
- To size household rainwater harvesting, CONAGUA starts from the WHO's minimum allowance of 50 to 100 liters per person a day, and allows more where local rainfall permits (CONAGUA, January 2025) \[3\].

## Who owns the groundwater in Mexico?

Water is a national resource. The Ley de Aguas Nacionales (National Waters Law) states that "the exploitation, use, or harnessing of national waters shall take place through a concession or assignment granted by the Federal Executive through 'the Commission'" \[1\] (translation) — that is, CONAGUA. In the Paredón aquifer, that title has been mandatory since the 2013 suspension \[2\].

Every concession is recorded in the National Public Water Registry (REPNA), which the law defines as the registry that "provides information and legal certainty to national-water users and inherent assets through the recording of concession titles, assignments, and discharge permits" \[1\] (translation). Article 23 of the law requires the title to state the holder, the aquifer, the point of extraction, the authorized volume, and the term, among other details \[1\].

## What is the state of the aquifer that supplies Paredón?

Amargos and Paredón sit on the Paredón aquifer, according to CONAGUA \[2\]; it is distinct from Saltillo–Ramos Arizpe (0510), to its south, which is Saltillo's main source of drinking water \[5\]. CONAGUA defines the Paredón aquifer with code 0508, assigns it 6,291 km² lying mostly within the municipality of Ramos Arizpe, Coahuila, and concluded in 2024 that there "is no volume available to grant new concessions", with a deficit of 39,033,049 m³ a year \[2\] (translation).

| Paredón aquifer (0508) indicator | Value | Source |
| --- | --- | --- |
| Surface area | 6,291 km² | CONAGUA, 2024 \[2\] |
| Average annual recharge | 23.6 hm³ | CONAGUA, 2024 \[2\] |
| Concessioned extraction (REPDA, as of Dec. 2022) | 59,333,049 m³/year | CONAGUA, 2024 \[2\] |
| Annual deficit | 39,033,049 m³ | CONAGUA, 2024 \[2\] |
| Ban on free well-drilling | In force since 5-Apr-2013 | CONAGUA, 2024 \[2\] |

## What should you ask before buying land in an arid zone?

One question organizes all the others: what is the concession title supplying this property, whose name is it registered under in the REPNA, and what volume does it cover? \[1\] "There's plenty of water here" or "the neighbor has a well" are not substitutes for a title number; this is information that should already exist, not a task for after closing. Anyone comparing [rural land in Coahuila](https://gruposerver.com.mx/en/blog/terrenos-campestres-coahuila-guia-compra/) or looking into [how to title land in the state](https://gruposerver.com.mx/en/blog/como-escriturar-terreno-coahuila/) should bring this question into the same conversation as the deed, and resolve any doubts with a notary or with CONAGUA.

## How does rainwater harvesting work in a desert home?

In January 2025, CONAGUA published technical guidelines for household rainwater-harvesting systems (SCALL), under the PROCAPTAR program \[3\]. The principle is simple: the roof channels water through gutters with a minimum 2% slope into a tank, first passing through a device that diverts the initial wash-off water, calculated at 0.40 to 0.80 liters per square meter of roof \[3\].

The volume that can be stored depends on the catchment area, the roof material's runoff coefficient (per standard NMX-AA-164-SCFI-2013), and local rainfall; CONAGUA sizes the system starting from the WHO's minimum allowance of 50 to 100 liters per person a day \[3\]. That logic — roof, slope, and storage built into the plans, not bolted on later — is worth checking in any [home designed for the desert climate](https://gruposerver.com.mx/en/blog/arquitectura-sostenible-clima-desertico/).

## Can household water be reused in the garden?

The federal quality benchmark for reusing treated wastewater is NOM-003-SEMARNAT-1997, binding on public entities and on any third parties that provide the public service; for watering parks and gardens it sets caps of 240 MPN/100 ml fecal coliforms, no more than 1 helminth egg per liter, 15 mg/l grease and oils, 20 mg/l BOD₅, and 20 mg/l total suspended solids \[4\]. In a private home those limits work as a design benchmark, not a permit: the residential case is decided by the environmental authority and the project developer.

As for what to plant, the Coahuila desert has its own [biodiversity adapted to aridity](https://gruposerver.com.mx/en/blog/desierto-coahuilense-biodiversidad/), species that need less added irrigation than a broadleaf lawn, which competes for the same resource already running a deficit \[2\].

## Frequently asked questions

### Can I drill a well on my own land without a permit?

No, in the Paredón aquifer: the suspension of free well-drilling has been in force there since 2013. Outside restricted zones, the law allows groundwater to be freely drilled (art. 18).

### Why does the Paredón aquifer matter for a project in Amargos?

Because it is the aquifer covering that area, in the municipality of Ramos Arizpe, and CONAGUA reported it in 2024 with no volume available for new concessions and a deficit of 39,033,049 m³ a year.

### How much rainwater can I capture at a desert home?

It depends on your roof's area and material (runoff coefficient) and on local rainfall; CONAGUA sizes the system to a minimum allowance of 50 to 100 liters per person a day.

### Can I water the garden with shower water?

NOM-003-SEMARNAT-1997 sets reuse limits for public services, including garden irrigation, and binds public entities and third-party providers; for a private home, check with the environmental authority or the municipal water operator.

### Who do I ask for a development's concession title?

The seller, while independently verifying its registration in the REPNA; questions about validity go to the relevant CONAGUA Organismo de Cuenca or, for the deed itself, to a notary.

## Topics

- Ex Hacienda Amargos
- Paredón
- Coahuila
- Grupo Server
- Ramos Arizpe
- Saltillo
- CONAGUA
- SEMARNAT
- Public Property Registry

## Sources

- [\[1\] Ley de Aguas Nacionales, current text — Cámara de Diputados del H. Congreso de la Unión (last amended DOF December 11, 2025)](http://www.diputados.gob.mx/LeyesBiblio/pdf_mov/Ley_de_Aguas_Nacionales.pdf)
- [\[2\] Actualización de la disponibilidad media anual de agua en el acuífero Paredón (0508), estado de Coahuila — CONAGUA, Subdirección General Técnica, Gerencia de Aguas Subterráneas (2024)](https://sigagis.conagua.gob.mx/gas1/Edos_Acuiferos_18/coahuila/DR_0508.pdf)
- [\[3\] Lineamientos técnicos: Sistema de Captación de Agua de Lluvia a Nivel Vivienda (SCALL), version 3.4 — CONAGUA, Programa Nacional para Captación de Agua de Lluvia y Ecotecnias en Zonas Rurales (PROCAPTAR) (January 2025)](https://www.gob.mx/cms/uploads/attachment/file/976468/Lineamientos_t_cnicos_SCALL_2025.pdf)
- [\[4\] NOM-003-SEMARNAT-1997, Que establece los límites máximos permisibles de contaminantes para las aguas residuales tratadas que se reusen en servicios al público — Secretaría de Medio Ambiente y Recursos Naturales, published in Mexico's Diario Oficial de la Federación (September 21, 1998)](https://www.gob.mx/cms/uploads/attachment/file/311363/NOM_003_SEMARNAT.pdf)
- [\[5\] Actualización de la disponibilidad media anual de agua en el acuífero Saltillo–Ramos Arizpe (0510), estado de Coahuila — CONAGUA (2024)](https://sigagis.conagua.gob.mx/gas1/Edos_Acuiferos_18/coahuila/DR_0510.pdf)

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