Market Intelligence

Water Risk and the San Miguel de Allende Aquifer

The federal water authority's own determination for the aquifer under this city records an annual deficit of nearly 62 million cubic metres and states that no volume remains for new concessions. It is the most consequential constraint on building here, and almost no page written for buyers mentions it.

Updated 2 September 2026

−61,984,190 m³
Annual deficit, Río Laja aquifer: Zero
Volume available for new concessions: 1958
First well-drilling ban over Allende: +2.7 million m³
Growth in the deficit since 2015

The figure no listing mentions

CONAGUA, the federal water commission, publishes a determination of groundwater availability for every aquifer in Mexico. The one beneath San Miguel de Allende is aquifer 1108, Cuenca Alta del Río Laja, and it also serves Dolores Hidalgo, San Felipe and San Diego de la Unión.

Its 2024 determination sets annual recharge at 139.7 million cubic metres. Registered extraction, drawn from the REPDA concession register with a cut-off of 30 December 2022, is 201.684190 million cubic metres. The arithmetic is not complicated:

139.7 − 0.0 − 201.684190 = −61.984190 million cubic metres a year.

CONAGUA then states the consequence directly: no existe un volumen disponible para otorgar nuevas concesiones; por el contrario el déficit es 61,984,190 m³ anuales. There is no volume available to grant new concessions. On the contrary, the deficit is 61,984,190 cubic metres annually.

That is a primary federal document about the water under this city, and it is the most decisive supply constraint on new development anywhere in the municipality. It appears on essentially no page written to sell property here.

It is getting worse, not stabilising

One determination is a snapshot. Two make a direction.

The earlier determination for the same aquifer, published in the Diario Oficial de la Federación on 20 April 2015 against a REPDA cut-off of 30 June 2014, recorded recharge of 139.7 million cubic metres against registered extraction of 199.026301 million, for a deficit of 59.316301 million cubic metres a year.

	DOF, 20 April 2015	CONAGUA, 2024
Annual recharge	139.7 hm³	139.7 hm³
Registered extraction	199.03 hm³	201.68 hm³
Annual deficit	−59.32 hm³	−61.98 hm³
Volume for new concessions	0	0

Recharge is unchanged in both documents. Registered extraction rose by roughly 2.7 million cubic metres a year, and the deficit widened by the same amount. Neither determination found any volume available.

Two cautions on reading that table. Registered extraction is what is on the concession register, which is not the same as what is actually pumped, and the two determinations use different register cut-offs a little over eight years apart. It is a record of the legal position tightening, which is what governs whether anything new can be built.

The wells were closed before the city grew

Groundwater here has been restricted for longer than most buyers assume. A partial veda — a well-drilling ban — was decreed on 23 October 1958 covering Dolores Hidalgo, San Diego de la Unión and Allende. A further decree on 24 September 1964 extended it to the remainder of Allende and San Diego de la Unión. CONAGUA’s 2024 documentation cites both as still governing.

So the position facing a buyer today is a sixty-year-old drilling restriction sitting on top of a determination that no new concession volume exists. Anyone told that a property can simply have a well drilled, or an existing one deepened, is being told something that needs checking with CONAGUA before contracts are signed, not after.

What this does and does not tell you about prices

We are not going to convert a hydrological deficit into a percentage off your resale value, because no published study does that and inventing one would be worth less than nothing.

What can be stated honestly is the mechanism. Water availability constrains what can be built, which bears directly on the value of undeveloped land and on any project that would require a new concession. It bears on holding costs if water becomes more expensive over the period you own. And it bears on resale if the constraint becomes better understood among buyers than it is now — which is a reasonable expectation, given that it is documented federally and currently discussed almost entirely outside the property market.

None of that is priced into any figure we have seen published for this city. That is not a claim that values are wrong. It is a statement that one of the inputs is missing from the public conversation.

Water quality is a separate question, and a live one

Availability and quality are different problems. Independent monitoring in the region has reported elevated fluoride, arsenic, lead and mercury in various wells.

The only neighbourhood-level listing published for San Miguel de Allende comes from Discover San Miguel de Allende, reporting Caminos de Agua’s monitoring map, on 23 February 2022. It grouped colonias as follows:

Most contaminated: Santa Cecilia, Insurgentes, Mexiquito, San Rafael, Linda Vista, Olimpo, Ejido de Tirado, Centro, Las Brisas, Santa Julia
Moderately contaminated: San Luis Rey, Fraccionamiento Insurgentes, Francisco Villa, Obraje, Guadalupe, Providencia, San Antonio, San Martín
Cleanest: Independencia, Azteca, Guadiana, Valle del Maíz, Allende, Malanquín, Palmita, Luciérnaga, La Luz, Los Frailes, La Lejona

Centro — where most foreign buyers concentrate — sits in the most contaminated group.

We reproduce that list because it is the only such information published, and we attach the warning it needs: a single source, several years old, with no numerical thresholds, no well counts and no stated study period. It is a reason to commission a water test on the specific property you are considering. It is not a measurement of that property.

What is not knowable

Being straight about the limits of this page matters as much as the figures in it:

Actual extraction, as opposed to registered extraction. The deficit is computed from the concession register. Unregistered pumping is by definition not in it.
A current depletion rate. Figures circulate for how fast the water table is falling and for the degree of overexploitation, attributed to the Comisión Estatal del Agua de Guanajuato. We could not trace those specific numbers to a single dated primary document, so we have not put them in the stat strip. The direction they describe is corroborated by the CONAGUA determinations, which are primary and which we did verify.
Property-level supply. Whether a given house is on municipal supply or a well, what that well yields, and what its water contains are all specific to the address and answerable only by inspection.
Any price effect. Nobody has published one.

What to do before you buy

None of this argues against buying in San Miguel de Allende, and we have nothing to gain from your decision either way. It argues for four questions that a commission-motivated source has no reason to raise:

Is this property on municipal supply or on a well? Get it in writing.
If there is a well, what is its concession status with CONAGUA, and does it transfer with the sale?
What does a current, independent water test on this property show — not on the colonia?
If any part of the plan involves building, subdividing or adding capacity, what water does that require, and where would a new concession come from given that CONAGUA records none as available?

A buyer who asks those four questions and proceeds is making an informed decision. A buyer who has never been shown the deficit is not making a decision at all.

Sources

CONAGUA, Subdirección General Técnica, Gerencia de Aguas Subterráneas — Determinación de la disponibilidad de agua subterránea, acuífero 1108 Cuenca Alta del Río Laja. Recharge 139.7 hm³/year, registered extraction 201.684190 hm³/year, availability −61.984190 hm³/year, and the statement that no volume exists for new concessions · Study dated 2024; REPDA concession register cut-off 30 December 2022
CONAGUA, published in the Diario Oficial de la Federación — the prior determination for the same aquifer, recording a deficit of 59.316301 million m³/year, which is what establishes that the shortfall is long-standing and widening rather than a single bad year · Published in the DOF 20 April 2015; REPDA cut-off 30 June 2014
CONAGUA aquifer determination document, section 1.2.1 Decretos de Veda — partial well-drilling ban decreed 23 October 1958 over Dolores Hidalgo, San Diego de la Unión and Allende, extended by decree of 24 September 1964 to the remainder of Allende and San Diego de la Unión · Decrees of 1958 and 1964, cited in 2024 CONAGUA documentation as still governing
Caminos de Agua, Urban Water Initiative — a local water NGO citing CONAGUA, INEGI, GIZ Mexico and INECC for Presa Allende at 15 per cent of capacity, regional warming of about 1°C, sevenfold urban expansion in San Miguel between 1997 and 2016, and a projected 192 per cent rise in water prices by 2060 · Page references 2021 reservoir data; publication year not stated on the page
Discover San Miguel de Allende, reporting Caminos de Agua's monitoring map — the only neighbourhood-level water quality listing published for this city · Published 23 February 2022

Common Questions

Is there enough water in San Miguel de Allende?

Not on the federal water authority's own arithmetic. CONAGUA's determination for the Cuenca Alta del Río Laja aquifer, the aquifer beneath San Miguel de Allende, records annual recharge of 139.7 million cubic metres against 201.68 million cubic metres of registered extraction, leaving a deficit of 61,984,190 cubic metres a year. The document states in plain terms that there is no volume available to grant new concessions. That is a statement about the legal and physical availability of groundwater, not a forecast, and it is the single most decisive constraint on new development anywhere in the municipality.

Can you drill a well on a property in San Miguel de Allende?

Not freely, and not on the assumption that a permit will follow. A partial well-drilling ban, a veda, was decreed over Dolores Hidalgo, San Diego de la Unión and Allende on 23 October 1958, and extended by decree on 24 September 1964 to the remainder of Allende and San Diego de la Unión. CONAGUA's own aquifer documentation cites both decrees as still governing. Combined with a determination that no volume is available for new concessions, a buyer should treat any assurance that a well can simply be drilled or deepened as something to verify with CONAGUA before purchase rather than after.

Does the water situation affect property values in San Miguel de Allende?

No published study measures that, and we will not pretend otherwise. What can be stated is the mechanism rather than the magnitude. Water availability constrains what can be built, which affects the value of undeveloped land and of projects that depend on new concessions. It also bears on holding costs if water becomes more expensive, and on resale if the constraint becomes more widely understood among buyers than it is today. None of that is currently priced into any figure we have seen published, because no source has attempted it.

Is the tap water safe to drink in San Miguel de Allende?

Independent monitoring has reported elevated fluoride, arsenic, lead and mercury in various wells across the region, and a neighbourhood map published in February 2022 by Discover San Miguel de Allende, reporting Caminos de Agua's monitoring, placed Centro itself in the most contaminated group alongside Santa Cecilia, Insurgentes, Mexiquito, San Rafael, Linda Vista, Olimpo, Ejido de Tirado, Las Brisas and Santa Julia. That article is now several years old, gives no numerical thresholds, no well counts and no study period, so treat it as a prompt to test rather than as a measurement. Water quality is a live due-diligence item for any property on well water rather than municipal supply.

Which San Miguel de Allende neighbourhoods have the cleanest water?

The same February 2022 map listed Independencia, Azteca, Guadiana, Valle del Maíz, Allende, Malanquín, Palmita, Luciérnaga, La Luz, Los Frailes and La Lejona as cleanest, with San Luis Rey, Fraccionamiento Insurgentes, Francisco Villa, Obraje, Guadalupe, Providencia, San Antonio and San Martín moderately contaminated. We repeat that list because it is the only neighbourhood-level water information published for this city, and we attach the same warning: one source, four years old, no thresholds and no method. It is a starting point for a water test on a specific property, not a substitute for one.

Should water risk stop me buying in San Miguel de Allende?

That is not a question we will answer for you, because we do not know your property, your timeline or your tolerance, and we earn nothing either way. What we will say is that the constraint is documented at primary-source level, it has worsened between the two CONAGUA determinations on record, and it is absent from essentially every page written to sell you a house here. A buyer who has read the CONAGUA determination and still wants the property is making an informed decision. A buyer who has never been told the deficit exists is not.

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