Portugal Ring-Fences 23 Alentejo Drinking-Water Boreholes, but Draws the Wider Protection Zones Only Where the Groundwater Is Already Healthy

Sixteen government orders published in Thursday's Diário da República (Official Gazette) drew legal protection zones around 23 boreholes and wells that supply drinking water to about 9,100 people in the Alentejo. They came into force on Friday. Together they cover Alcácer do Sal, Sines and Santiago do Cacém, and they change what may lawfully be done on the ground above those water sources.

The orders, Portaria n.º 351/2026/1 through n.º 366/2026/1, were signed by the Secretary of State for the Environment, João Manuel do Amaral Esteves, on 6 and 10 August and published on 20 August in Diário da República n.º 161/2026, Série I. Each enters into force the day after publication, which makes Friday, 21 August the first day the restrictions bite.

What the orders actually cover

All 23 sources belong to AgdA, Águas Públicas do Alentejo, S. A., the regional public water company, and all of them are groundwater: boreholes (furos), dug wells (poços) and drain galleries (drenos). The Agência Portuguesa do Ambiente (Portuguese Environment Agency, or APA) proposed each delimitation on the basis of studies AgdA supplied, in two batches: an APA file dated 26 February 2026 for the Alcácer do Sal group, and one dated 23 March 2026 for the Sines and Santiago do Cacém group.

The scale is small and intensely local. Ten of the 16 orders sit in Alcácer do Sal, covering 17 abstractions that between them serve 4,382 people with about 1,760 cubic metres a day. Five orders sit in Santiago do Cacém, covering five abstractions serving 4,451 people with about 1,348 cubic metres a day. A single order covers the Sonega borehole in Sines, which serves 268 people. The largest single source is the Santiago Fidalgo/Furo 7 borehole, which supplies 2,631 residents of Santiago do Cacém with 821 cubic metres a day. The smallest, the Lousal/PS1/Pomarinho well, contributes to the supply of 33 people at Azinheira dos Barros, in the neighbouring municipality of Grândola.

Three zones, and why only some of them were drawn

Portuguese law builds a protection perimeter in three rings, under Decreto-Lei n.º 382/99 of 22 September, the rules for delimiting protection perimeters around public-supply groundwater sources. The immediate zone is the small patch of ground at the wellhead. The intermediate zone is wider. The extended zone is wider still, and is meant to catch pollution travelling through the aquifer from further away.

Every one of the 16 orders draws the immediate zone. Inside it, the rule is close to absolute: no installation and no activity of any kind is permitted, except work whose object is the conservation, maintenance or better operation of the abstraction itself. The land must be fenced and kept clear of any waste, product or liquid capable of leaching something unwanted into the water.

Only three of the 16 orders go further and draw the intermediate and extended zones as well. All three are in Santiago do Cacém: the São Francisco da Serra borehole, the Santiago Fidalgo/Furo 7 borehole, and the Ermidas-Sado source. Five other orders state expressly that the intermediate and extended zones still require a study of their own from AgdA, and that the eventual delimitation will arrive as an amendment to the order just published. The remaining eight simply delimit the immediate zone and say nothing at all about the wider rings.

The pattern in the water quality data

Each order records how the underlying body of groundwater was rated in the relevant river-basin management plan, and the split is stark.

All ten Alcácer do Sal orders sit over aquifers already classified with an overall status of medíocre, the Portuguese rating for poor: the Bacia do Tejo-Sado/Margem Esquerda system in the Tejo e Ribeiras do Oeste basin plan (RH5), the Bacia do Tejo-Sado Indiferenciado da Bacia do Sado, and the Maciço Antigo Indiferenciado da Bacia do Sado, both in the Sado e Mira plan (RH6). All six orders in Sines and Santiago do Cacém sit over water rated Bom, or good: the Zona Sul Portuguesa da Bacia do Sado, the Bacia de Alvalade and the Orla Ocidental Indiferenciado da Bacia do Sado.

Set the two facts side by side and the result is uncomfortable. The three sources that got the full three-ring treatment, with the real land-use restrictions attached, all draw on groundwater the state has already judged to be in good condition. Every source drawing on water the state has already judged to be poor got a fenced wellhead and nothing more. That is not a claim about intent: the orders are silent on why the wider studies were completed in one place and not another. But it is what the published record shows on the day the rules took effect.

What the wider zones would have banned

The three complete orders show the size of what the other 13 areas are not yet getting. In the intermediate zone, the banned list runs to fifteen items: aeronautical infrastructure; garages and vehicle service stations; stores of radioactive material, hydrocarbons and hazardous waste; fuel stations and motorway service areas; the transport of hydrocarbons, radioactive materials or other dangerous substances; toxic-product pipelines; dumps and landfills of every class, hazardous, non-hazardous and inert alike; the discharge and spreading of livestock effluent and sewage sludge; cesspits in areas where public sewerage exists; sewer collectors and wastewater treatment plants; polluting industry; cemeteries; quarries, mines and any extractive industry; scrapyards and waste-management operations; and unlined lakes, pits and excavations, a category that expressly includes sinking a new private borehole where a mains connection is available. Disused boreholes have to be cemented shut.

A second list is conditioned rather than banned. Grazing, farming and livestock are allowed only where they cause no significant impact on water resources. New buildings are allowed only if connected to municipal sewerage or, failing that, fitted with a fully sealed tank. Septic tanks are permitted only against strict watertightness criteria, must be replaced or converted if they do not meet them, and must be decommissioned altogether once mains sewerage reaches the area.

The extended zone is looser but still real: it bans refineries and chemical plants, dumps and landfills, dangerous-substance transport and storage, toxic pipelines, septic tanks where sewerage exists, and the spreading of livestock effluent and sewage sludge. Quarrying, cemeteries, filling stations and scrapyards move into the conditioned column, subject to sealed surfacing, effluent capture and water-quality monitoring.

Nineteen years in the making

These delimitations are not early. Decreto-Lei n.º 226-A/2007, the regime governing the use of water resources, came into force on 1 June 2007, and its article 90 gave the holders of existing abstractions one year to file protection-perimeter delimitation studies with the regional water authority. Article 43 of the same law goes further: the title authorising a public-supply abstraction presupposes that its protection perimeter has already been delimited.

Nineteen years later, these particular Alentejo sources have been supplying towns and villages while their perimeters were still undrawn, and for 13 of the 23 the two outer rings remain undrawn today. The immediate zone must also be signposted by the holder of the abstraction, so the practical marker for residents will be new fencing and signage appearing around wellheads over the coming months.

Portugal has been tightening groundwater rules elsewhere in the south. In May the environment agency eased its drilling ban across most Algarve water bodies while keeping several frozen, including part of the left bank of the Tejo-Sado system that these Alcácer do Sal orders now touch. The mainland entered meteorological drought this month after its driest July of the century, which makes the condition of small municipal sources a live question rather than an administrative one.

What This Means for Expats

• Check before you buy rural land in these three councils. The orders are published with coordinate tables and cartography, not with addresses. If you are buying a plot in Alcácer do Sal, Sines or Santiago do Cacém, ask the seller and the câmara municipal whether any part of it now falls inside a protection perimeter, and get the answer in writing before the deed. The restriction runs with the land, not with the owner.
• Septic tanks are the item most likely to catch a foreign owner. Rural Portuguese properties frequently rely on a fossa. Inside an intermediate or extended zone, a traditional soakaway tank is not compliant; only a strictly sealed tank is, it must be emptied rather than allowed to leach, and it has to be abandoned once mains sewerage arrives.
• Do not assume your own borehole is safe. Sinking a new private borehole is on the banned list inside an intermediate zone wherever a mains connection is possible, and is conditioned inside an extended zone. Existing private abstractions that are taken out of service have to be cemented shut, not simply capped and forgotten.
• The penalties are environmental, not municipal. Handling, depositing or storing harmful products next to a public abstraction or inside its immediate protection zone is a very serious environmental infringement under article 81 of Decreto-Lei n.º 226-A/2007. Under the framework law on environmental infringements, that band runs from 10,000 to 100,000 euros for an individual acting negligently, and from 20,000 to 200,000 euros where intent is proved.
• Expect more orders, and expect them to be wider. Thirteen of these 23 sources still have their intermediate and extended zones to come. When those arrive, they will restrict a far larger area than the fenced wellheads published this week, and they will arrive as amendments to orders most landowners will never have read.

The immediate practical effect of Friday's rules is modest: a few fenced squares of ground in three Alentejo councils. The longer effect depends on studies AgdA has not yet delivered. Until it does, the state has protected the wellheads of its poorest-quality aquifers and left the recharge areas above them, where farming, septic tanks and private boreholes actually sit, exactly as they were. Anyone buying land in the Alentejo belt that has drawn record farmland investment should treat the published perimeter as a floor on the restrictions, not a ceiling. The environment agency has shown elsewhere this month, in the fish kill on the Corgo at Vila Real, how quickly a single discharge can undo a water body's status, and it has just cleared a 468 million euro logistics park at Grândola, in the same stretch of country these boreholes serve.