Written by Rikard · 14 years in construction and owner-side project management · €150M+ in governed project value.
On most Greek islands and in the countryside a house either sits on a municipal main and a sewer, or runs on its own arrangements: a borehole, a cistern filled by rain or tanker, and a septic or sealed tank in the garden. Which one you are buying decides your running costs, your summer and your legal exposure.
The listing will say “water and electricity connected” or “private well and tank” and leave it there. An independent pre-purchase property inspection starts where the listing stops: where the water comes from, where it goes after the drain, what licences sit behind both, and what the seller’s tanker and emptying receipts say about the house in August. This article covers the systems you will meet on the islands and in rural Greece, the rules behind them, and the line between what an inspection can see and what needs a laboratory, a Greek engineer or a lawyer.
Mains, borehole, cistern or tanker: establish which
Where a municipal network exists it is run by the municipality or its water and sewerage company, the ΔΕΥΑ, and the first document to ask for is a year of bills. Island networks are built for the resident population and carry several times that load in July and August. In the dry summers of 2024 and 2026 municipalities in the Cyclades, the Dodecanese, the Ionian and the Sporades declared water emergencies, cut supply at night, restricted the filling of pools and in one case had the navy ship water in. Desalination has become the standard answer and dozens of plants now run in the Aegean, but new units have arrived late and ageing pipes lose a good share of what they produce. A mains connection on an island is a question of pressure and continuity in high season, not only of whether a meter exists. Ask the neighbours about August, and read the roof tank and booster pump as the household’s own answer.
Outside the network the house carries its own supply: the στέρνα, a cistern under the terrace that collects winter rain from the roof and is topped up by tanker lorry when it runs low, or a borehole with a pump, a pressure vessel, often a filter or softener, and storage tanks whose volume the listing will quote. None of this is a defect. It is a running cost and a dependency, and the delivery receipts and the pump’s electricity bills show how large it is.
Boreholes and wells: the licence and the register
A borehole in Greece is not a private matter. Under Law 3199/2003 as amended, abstracting water and carrying out works to exploit it require a licence, issued by the Decentralised Administration on the recommendation of its Water Directorate. Joint ministerial decision 146896/2014 sets the licence categories, the file and the period of validity, and since 2014 every abstraction point, in use or not, has had to be entered in the national register of abstraction points, the ΕΜΣΥ. The registration code or certificate is required in the notarial deed when a property with a borehole changes hands, and at least one water directorate treats replacing or deepening a borehole as licensable work in its own right. Whether the licence exists, in whose name, for which use and quantity and until when is for your Greek lawyer before any deposit, not for the seller’s assurance that everyone has one.
The licence does not tell you whether the water will be there. On the drier islands aquifers recharge poorly, and in 2024 irrigation wells on at least one Cycladic island turned brackish as levels dropped and seawater moved in. Yield, drawdown and salinity are questions for a hydrogeologist. The inspection records what the borehole and its equipment look like and how the system behaves when the taps run; it does not measure the aquifer.
Water quality: who tests what
Public supplies fall under Directive (EU) 2020/2184, transposed in Greece by joint ministerial decision 27829/2023, as amended in 2025, which places monitoring on the water suppliers and covers water delivered by tanker as well as by pipe. Greece has used the directive’s option to leave individual supplies below ten cubic metres a day or fifty persons outside the regulation, unless the water is supplied as part of a commercial or public activity, while still requiring that such water meets the quality specifications of its annexes. A private borehole or cistern serving one house therefore sits outside any public monitoring programme, and testing it is the owner’s responsibility, not the municipality’s. The World Health Organization’s guidance for small and household supplies is built for this gap, around sanitary inspection of source and storage, and its background document on nitrate notes that septic tanks and pit latrines are a typical source of contamination in private wells and should not be sited near one. That is the reason the Greek distances below exist.
If you intend to drink from a borehole or a cistern, commission a laboratory sample before completion. The inspection can tell you that the lid is broken, the overflow runs back into the tank and the chlorinator is empty. Only a laboratory tells you what is in the water.
Septic tank, sealed tank or small treatment plant
Where there is no sewer, health regulation Ε1β/221/1965 on the disposal of sewage still sets the rules for small private systems, and the Ministry of Health has confirmed that it continues to apply to domestic wastewater after the 2012 waste law. Three arrangements are common. A septic tank proper is a watertight settlement tank whose overflow goes to a soakaway or absorption pit; the regulation places the tank at least 15 metres from any spring or well that a household depends on for water where no mains supply exists, and the absorption pit at least 30 metres from such wells, springs and bathing shores, and forbids absorption pits on very permeable ground where water sources could be contaminated. A sealed tank, the στεγανός βόθρος, has no outlet, is sized for a set number of days of storage and is emptied by tanker to a disposal point the municipality has approved. A small treatment plant, the compact unit fitted to many new villas, treats the water and disposes of it by subsurface irrigation; under decision 145116/2011 as amended, systems up to 50 population equivalents need no reuse permit and their design and disposal method are approved with the building permit. In every case the drainage design belongs to the permit file, so the first question on site is whether the tank you can see is the tank the drawings show.
The running reality is easier to describe. A system sized for a family carries a full villa of guests in August, plus the pool backwash, and it shows: slow drains, a tanker on speed dial, a smell on the terrace on still evenings and a green patch in the garden where nothing else is green. Ask for the emptying receipts for the last two summers and note the interval. Ask where the tanker parks and whether its hose reaches. A sealed tank emptied every fortnight in season is a cost the listing did not mention; a soakaway that has stopped soaking is a replacement.
Sewer networks: now and later
The EU urban wastewater directive of 1991 requires collecting systems for agglomerations above 2,000 population equivalents and allows individual systems where a network is not justified, which is why so much of island and rural Greece legally runs on tanks. The 2024 recast lowers the threshold to 1,000 population equivalents, with a 2035 deadline for the smaller settlements and room for extensions, so villages that have never had a sewer are now on a timetable. When a network arrives, connection is not optional: the 1965 regulation obliges owners to connect where a sewer exists, Law 5314/2026 lets each ΔΕΥΑ set in its regulation which properties must connect and how, and published municipal regulations require the owner to put the old cesspit out of use at their own cost and forbid emptying it into the new sewer. The connection charge and the works inside the plot land on whoever owns the house when the network reaches the street. Ask the municipality what is planned; the hidden costs of buying property in Greece are often of this kind.
What the inspection covers
The pre-purchase inspection treats water and drainage as a visual and functional check. We locate the source, the storage and the drainage installation and record what is there: borehole head, pump and pressure vessel; cistern or tank with its lid, overflow and inlet; filters, softener, UV unit or chlorinator and their service state; the septic or sealed tank with its access lid, inspection chamber and vent, and its distance from any well on the plot. We run taps and showers together, watch pressure and recovery, listen to the pump cycle, look for leaks and damp around the plant, and read the ground around the tank and soakaway for overflow, odour and standing water. We check whether a tanker can reach the tank and whether the layout matches the permit drawings.
We do not take water samples and we do not pressure test pipework or tanks, and the report says so. Water quality goes to an accredited laboratory, yield and salinity to a hydrogeologist, the drainage design and any compact unit to a Greek engineer, and the borehole licence, the ΕΜΣΥ registration and the municipality’s sewer plans to your lawyer. The inspection gives you the list of questions those specialists must answer, written against the property rather than the brochure.
The sequence for the buyer
Settle the source first: bills and the August question on the mains, licence and registration code to the lawyer and a hydrogeologist’s view on a borehole, tanker receipts on a cistern. Then settle the drain: which tank, where, what the permit shows, how often it is emptied and whether a sewer is coming. Add these items to the checks before signing a property contract in Greece and the property risk checklist, and on a new build to the snagging list for a villa, because a compact treatment unit that was never commissioned is a defect from day one.
Frequently Asked Questions
Do I need a licence for a borehole in Greece?
Yes. Under Law 3199/2003 as amended and joint ministerial decision 146896/2014, abstracting groundwater and drilling or altering a borehole require a licence from the Decentralised Administration, and every abstraction point must be registered in the national register, the ΕΜΣΥ. The registration code is required in the deed when the property changes hands. Have your Greek lawyer confirm the licence, its holder, use and expiry before you commit.
How far must a septic tank be from a well in Greece?
Health regulation Ε1β/221/1965 places a septic tank at least 15 metres from a spring or well that is relied on for water supply where no mains exists, and an absorption pit at least 30 metres from such wells, springs and bathing shores, and prohibits absorption pits on very permeable ground where water sources could be contaminated. The regulation is old and written in general terms, so confirm the position for a specific plot with your Greek engineer and the local health authority.
Can I drink the water from a borehole or cistern on a Greek island?
Only after a laboratory test. The EU drinking water directive and its Greek transposition place monitoring on public and commercial suppliers, and Greece has exempted individual supplies serving one house from public monitoring, so nobody tests a private borehole or cistern unless the owner does, and the regulation still expects that water to meet the drinking water specifications. WHO guidance for small supplies pairs a sanitary inspection of source and storage with laboratory analysis, and warns that septic tanks near a well are a common source of nitrate.
What is the difference between a septic tank and a sealed tank in Greece?
A septic tank is a watertight settlement tank whose overflow goes to a soakaway, so the liquid leaves and only sludge is pumped out at intervals of years. A sealed tank, the στεγανός βόθρος, has no outlet, stores everything and is emptied by tanker at intervals of weeks in a busy house. A small treatment plant treats the water and disposes of it by subsurface irrigation. Which one the house has, and which one the permit shows, decides your running cost.
Will I have to connect to a sewer if the municipality builds one?
In general, yes. The 1965 health regulation requires owners to connect where a sewer exists, and under Law 5314/2026 each municipal water and sewerage company sets in its regulation which properties must connect and how; published regulations also require the old cesspit to be put out of use at the owner’s cost. The 2024 recast of the EU urban wastewater directive extends collection obligations to settlements of 1,000 population equivalents by 2035, so ask the municipality what is planned.
Before you buy on a Greek island
Send the listing, the plot plan and whatever the seller holds on water and drainage: bills, the borehole licence, tanker and emptying receipts, the permit drawings. We review them before you travel and inspect the systems on site before contracts are signed. Submit the property details here: kgnordic.com/contact
Sources
Sources checked 28 October and 2 November 2026. Legal questions are for your Greek lawyer.