Water is infrastructure. Water is ecology. On a rural site in North Portugal, water is also one of the most uncertain variables in the entire project. This is the honest account of how we found, stored, distributed, and returned every drop.
## Where the Water Comes From
**The spring.** Our site has a small natural spring on the upper slope that runs reliably from October through May and reduces to a trickle in summer. We've captured it into a 3,000-litre stone-and-lime-mortar settling tank and piped it by gravity to a storage cistern near the main building. Spring flow in winter: approximately 800L/day. Summer: 50–150L/day. Not sufficient for full guest operations alone.
**The borehole.** Drilled to 38m in Year 1 at a cost of €9,400. Yield tested at 2.2 m³/hour (approximately 53 m³/day continuous, though we never pump anywhere near this rate). The borehole gives us reliable year-round supply independent of seasonal rainfall variation. Its pump (a 750W submersible Grundfos unit) is powered by solar during the day and from batteries at night.
**Rainwater harvesting.** A 20,000-litre buried HDPE cistern collects runoff from the main building roof and the workshop roof. Used for garden irrigation and toilet flushing — not for drinking water. In a typical Norte winter, this fills completely in November and stays full through April.
## How Water Moves Around the Site
Everything runs by gravity where possible. The borehole pump fills a 10,000-litre header tank on the high point of the site (we built the small stone platform for it in Year 1). From the header tank, water distributes by gravity pressure to all accommodation units, the kitchen, the bathrooms, and the garden taps. Zero pump energy required for distribution.
The kitchen and bathrooms feed into the primary wastewater treatment system (Imhoff tank + reed bed — see BLOG-007). The garden grey water goes directly to a mulch-filled drainage trench around the orchard.
## The Swales
Before we planted anything significant, we ran one earthworks day with a mini-digger in October. We created three on-contour swales — shallow, level channels dug along the slope contour lines — above the main food forest and orchard areas.
A swale does one thing: it stops water running downhill during heavy rain and instead holds it in place, allowing it to sink slowly into the soil rather than running off. On our granitic hillside, which has naturally low water retention, this was the highest-ROI intervention we made. Trees planted on the downslope berm of the swales established visibly faster and showed no drought stress in their first summer.
Cost of the earthworks day: €680 for digger hire + operator.
## The Pond Water Balance
The biological swimming pond holds approximately 180,000 litres (180 m³) of water. We designed the water balance carefully: evapotranspiration losses in summer (estimated 3–5mm/day of surface area, approximately 500–800L/day) are replaced by natural rainfall in the wet season and by borehole top-up in summer. In a dry July, we top up approximately 18,000L from the borehole — a meaningful but manageable draw on our supply.
We added a polishing pond (overflow wetland) below the biological pond that captures any overflow and allows it to percolate back into the groundwater. Net water export from the system is zero in a wet year; we're net consumers only during August.
## The Lesson
Rural water supply in North Portugal is abundant on average and uncertain in specifics. Our three sources (spring, borehole, rainwater) give us redundancy at every level — if any single source fails or reduces, the others compensate. That redundancy is the design goal. Single-source water dependency on a hospitality site is an unacceptable operational risk.
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*Water supply verification is our most emphatic due diligence recommendation for any rural Portugal site purchase.*