Field notes · Koh Samui

Koh Samui Well & Water Guides

How deep wells, pumps, filtration and villa water systems work on Koh Samui — drilling costs, water quality, pump faults and dry-season planning, explained by the team that drills and services wells on the island.

Roofed storage area beside a Koh Samui villa with two black polyethylene tanks: the raw tank fed from the borehole, its outlet passing through a filter vessel into the treated tank through an air gap, with overflow pipes to a drain and a booster pump feeding the house

Water Supply

Villa water storage done properly: raw and treated tanks, connecting several tanks, overflow, float valves and keeping them clean

Every villa has tanks and almost nobody designs them. They get bought by the litre, plumbed by whoever is on site and never opened again. This guide is about the part of storage that sizing leaves out: whether you need one tank or two, how several tanks should be connected, what the inlet, overflow and draw-off should look like, why big tanks still run dry, and how to keep the water in them clean.

November 5, 2026 · 10 min read

Villa plant room on Koh Samui with a variable-speed booster pump set: a horizontal stainless multistage pump drawing from a black storage tank, with its controller, a small blue pressure vessel and a gauge on the discharge into the house

Equipment

Choosing a booster pump for a villa: flow, head, constant pressure, and why it is not the well pump

The submersible pump gets water out of the ground. The booster pump is the one that decides whether the top-floor shower is any good. They are sized by different numbers, fail for different reasons and should never be asked to do each other's job. This guide covers the house-side pump: the two figures that size it, fixed speed against constant pressure, twin sets, suction, protection and the mistakes we are called out to undo.

November 2, 2026 · 10 min read

Villa plant room on Koh Samui with a whole-house water softener — resin vessel with control valve, brine tank and bypass valves — while a technician compares a hardness test vial against a colour chart

Water Supply

Hard well water and limescale in a villa: what hardness does, how to measure it, and when a softener is worth it

Scale on the shower screen, a water heater that takes longer every year, white crust on the pool tiles. Hardness is the mineral content most well owners never test for, because it is invisible in the glass and harmless to drink. It is not harmless to equipment. This guide explains where it comes from, how to put a number on it, and which of the treatment options actually make sense for a villa.

October 29, 2026 · 9 min read

New stainless submersible borehole pump on sawhorses beside a Koh Samui villa wellhead, motor end with the cable exiting under cable guards, a technician tightening the riser pipe and check valve onto the discharge

Equipment

Replacing a submersible well pump: diagnosis first, then the job itself

A silent pump is the start of a diagnosis, not the end of one. This guide walks through how a technician proves the pump is really at fault, what pulling it from a deep bore involves, why the replacement is rarely the same model, and what a proper commissioning looks like.

October 26, 2026 · 11 min read

Technician kneeling with a flashlight and clipboard beside a rusted, capless borehole casing stub in an overgrown corner of a Koh Samui villa garden, with a frayed cable and a broken pipe beside it

Guides

Unused and abandoned deep wells: preserve it, or decommission it properly

A well nobody uses does not simply sit there. Left open and unprotected, it becomes a pipe from the surface straight into the groundwater your neighbours drink. This guide covers what an idle bore turns into, how to keep one safely for later, and what proper decommissioning actually involves.

October 22, 2026 · 9 min read

Roofed water-plant area beside a Koh Samui villa: a capped borehole wellhead and a metered mains line both feeding one storage tank, with a booster pump and pressure vessel supplying the house

Water Supply

Running a private well alongside mains water: how to design a villa system with both

Plenty of villas on Koh Samui have a well and a mains connection. The question is not which one to keep — it is how to connect two sources so they back each other up without fighting, without contaminating anything, and without anyone having to be home to switch valves.

October 19, 2026 · 10 min read

Villa swimming pool on Koh Samui with a roofed service area holding storage tanks, a pump and a filter vessel, and the wellhead in front

Water Supply

Filling a pool from a deep well: yield, storage and water quality

Many villa pools can be filled and topped up from the property's own well. Two separate questions decide whether yours can: whether the well can give that much water without starving the house, and what the water does once chlorine goes in.

October 8, 2026 · 9 min read

Protected villa wellhead after heavy rain: raised blue casing with a sealed cap on a sloped concrete apron, rainwater draining away into a grassed swale

Guides

Protecting a deep well from surface contamination

Depth protects well water from a lot, but not from the top. The few metres where the casing meets the ground are where rain, runoff and wastewater find their way in, and they are entirely within the owner's control.

October 8, 2026 · 9 min read

Technician measuring the water level in a villa well with an electric water-level meter during the dry season on Koh Samui

Drilling

Why a deep well changes between Koh Samui's wet and dry seasons

The same well can give plenty in December and struggle in April without anything being wrong with it. A well isn't a tank of fixed size. Its useful supply rises and falls with the water around it, and the dry season is when that matters most.

October 8, 2026 · 9 min read

Technician measuring pump current with a clamp meter inside an open well-pump control panel on a villa pump house, wellhead in the background

Equipment

Power cuts, voltage swings and backup power for a villa well pump

The pump at the bottom of your well is the most expensive part of the water system to replace and the hardest to reach. On an island grid, the electricity feeding it does more damage than wear ever will, unless the control panel is built to stop it.

October 7, 2026 · 9 min read

Technician lowering a water-level meter tape into an existing well at an older villa while the prospective buyer watches

Guides

Buying a villa with a well on Koh Samui: what to check before you sign

"Own deep well" in a listing can mean a reliable borehole with ten years of records, or a hole in the garden with a tired pump and no history. A few days of checks before you commit tell you which, and what it will cost to live with.

October 7, 2026 · 9 min read

Pop-up sprinklers watering the lawn of a villa garden on Koh Samui in early morning light, with an irrigation tank and pump in the background

Water Supply

Watering a villa garden from a well: irrigation demand, pumps and storage

In the dry months the garden is often the biggest water user on a villa, bigger than the household. A well can carry it, but only if the irrigation is planned as its own system rather than hung off the house supply.

October 7, 2026 · 9 min read

Drilling

Inside a deep well: casing, screen, seal and pump explained

Once the rig leaves, almost all of your well is out of sight: tens of metres of pipe, gravel and seal that decide whether it gives clean water for decades or sand within a few years. This is what should be down there, and why.

October 3, 2026 · 9 min read

Whole-house water treatment plant beside a villa: storage tanks, pump, three filter vessels, cartridge filters, UV unit and pressure tank under a roofed shelter

Equipment

Whole-house water filtration for a villa well: how the system should be designed

There is no best filter. There is a system that fits one well, one villa and its busiest half-hour of the day. Most of the problems we fix in Samui plant rooms are design problems, not equipment problems.

October 3, 2026 · 9 min read

Technician measuring the salinity of a well-water sample with a handheld conductivity meter beside a wellhead at a beachfront villa on Koh Samui

Water Supply

Salty well water on Koh Samui: how saltwater intrusion reaches coastal wells

A well near the beach can run fresh for years and then turn brackish in a single dry season. The sea hasn't moved. What usually changed is how hard, how long and how deep the well is being pumped.

October 3, 2026 · 8 min read

Drilling

Preparing for well drilling on Koh Samui: access, space and the days on site

The drilling is the crew's job. Getting the rig to the right spot, keeping the garden and the neighbours on side, and knowing which decisions will come to you during the work all go better when the owner knows what's coming.

October 1, 2026 · 10 min read

Laboratory sample bottles of clear well water and a cool box on a villa terrace, with a deep-well wellhead and pump house behind

Water Supply

Is deep well water safe to drink? Water testing and treatment for Koh Samui villas

Clear, cold and odourless tells you very little about whether well water is safe to drink. A laboratory test does, and it also keeps treatment affordable, because you stop paying for stages your water doesn't need.

October 1, 2026 · 9 min read

Drilling

Deep well drilling quotes on Koh Samui: what a complete quotation should include

Two quotes for the same villa can be far apart and both be honest. The gap is almost always in what each one includes, and that is something you can check line by line before you sign.

October 1, 2026 · 8 min read

Technician in a villa pump room timing a fixed-speed booster pump with a phone while watching the pressure gauge and pressure switch on its discharge manifold, a pressure vessel beside it

Equipment

Why a well or villa pump keeps cycling: diagnose the controls before blaming the pump

A pump that keeps starting and stopping is usually obeying its controls exactly. The question is what those controls are reacting to: a vessel that has lost its air, a leak, a valve letting water back, a setting, or a tank level. Which one depends on how the system is built and on the pattern of the cycling.

September 13, 2026 · 9 min read

Technician's hand holding a tyre pressure gauge on the air valve at the top of a blue diaphragm pressure vessel, connected at its base by a braided hose to an isolating valve and drain on the booster line

Equipment

What a pressure tank actually does in a villa water system, and how to tell when it is too small or faulty

The small steel tank beside the booster pump is not a water store. It is a cushion of compressed air that lets the pump rest between starts. When the cushion goes, the pump starts on every draw and the pressure jumps. This guide explains how the vessel works, what it needs, and how to recognise one that has failed.

September 13, 2026 · 9 min read

Technician examining a jar of cloudy well water beside a borehole on Koh Samui

Water Supply

Sand or cloudy water from a deep well: what does it mean?

A glass of well water tells you more than most owners expect. What settles, what floats and what clears on its own each point somewhere different, and only some of them point at a filter.

September 13, 2026 · 7 min read

Technician preparing a submersible borehole pump and cable beside a deep well on Koh Samui

Equipment

How to choose a submersible pump for a deep well on Koh Samui

Horsepower is the last number to look at. A pump is matched to what the well can give and what the property needs, and both sides can be measured.

August 27, 2026 · 6 min read

Orange iron staining around well water pipework in a Koh Samui pump room

Water Supply

Why well water turns brown or orange: iron and manganese on Koh Samui

Water that leaves the pump clear and turns orange in the tank is not a mystery. The chemistry is ordinary and treatable, but the treatment should follow a water test, not a guess.

August 27, 2026 · 6 min read

Technician inspecting a villa water system with pressure tank and control panel on Koh Samui

Equipment

How often should a private well and pump be serviced on Koh Samui?

The borehole itself asks for very little. The pump, controls and tanks around it are machinery, and machinery rewards being looked at before it stops.

August 27, 2026 · 6 min read

Guides

How a villa water system works, from borehole to tap

Source, storage, pressure, treatment: the four stages every reliable villa water system on Koh Samui is built from, and how a weakness in one shows up in the others.

August 21, 2026 · 7 min read

Technician crouching at a villa booster pump set and reading the pressure gauge fitted on the discharge manifold, with a storage tank and a pressure vessel beside it

Equipment

Low water pressure in a villa: finding where the pressure is lost

Weak showers are a symptom with half a dozen possible causes between the storage tank and the tap. The fastest way to the right fix is to notice when the pressure is low, where, and whether the tank is full at the time. This guide turns those three observations into a diagnosis.

August 19, 2026 · 9 min read

Guides

Borehole maintenance: what a well needs to keep producing

A drilled well is a machine with moving parts and a service life. What annual servicing covers, why yields fade, and the two documents that make every future repair cheaper.

August 17, 2026 · 6 min read

Drilling

What happens during a deep-well drilling project on Koh Samui, from arrival to handover

A drilling project is loud for a few days, wet in places, uncertain at one or two moments and quiet for the rest. This guide follows the work in the order it happens, from the owner's side: what you will see, what it means, and when you will be asked to decide something.

July 12, 2026 · 9 min read

Technician lowering an electric water-level tape into a well casing during a pumping test, with the discharge running through a valve and a water meter to a gravel drain

Drilling

How well yield is actually measured, and why one flow number does not tell the whole story

"The pump gave 40 litres a minute" sounds like an answer, but it describes the pump on one afternoon, not what the well can keep giving. Yield is read from the water level: how far it falls while pumping, whether it settles, and how it comes back afterwards.

July 10, 2026 · 9 min read

Villa construction site on a hillside before the slab is poured, with water pipe and conduit sleeves standing in the formwork, a marked pad for future tanks, a capped well casing, and drawings held down by a hard hat

Guides

Planning the water system before building a villa or development on Koh Samui

Water decisions get built into a property long before anyone opens a tap. The slab fixes pipe routes, retaining walls fix where tanks can stand, and landscaping fixes where nobody will want to dig again. This is the order in which to settle the water system for one new villa, and what changes when several villas share a site.

July 8, 2026 · 10 min read

Drilling

What actually changes the cost of drilling a well on Koh Samui

There is no honest average price for a villa well on the island, because the bill is built from parts that change plot by plot. This guide takes the cost apart: which parts are fixed, which grow with every metre, which can only be confirmed once the bore is going down, and which of them you can influence before the rig arrives.

July 1, 2026 · 9 min read

Service yard behind a villa with a mains water meter in a ground-level box, a capped borehole wellhead on a concrete apron, and two water storage tanks on a plinth

Water Supply

Is a private well worth it for your Koh Samui property?

A well is not better or worse than mains water in general. It is worth drilling when it solves a real problem for this property, at a cost and with responsibilities the owner accepts. Six questions decide it: what mains water is available, how much the property needs, how much reliability matters, whether a well can be drilled here, what the water will need, and who will look after it.

June 28, 2026 · 9 min read

Technician measuring the running current of a well pump with a clamp meter on a single conductor inside an opened, isolated pump control panel

Equipment

Signs a well pump may be failing, and what can imitate pump failure

A submersible pump sits out of sight, so it gets blamed for every symptom at the tap. Some of those symptoms really are the pump. Many are the well, the wiring, the controls or the tank. Diagnose before pulling the pump: this guide shows how each symptom splits.

June 25, 2026 · 8 min read

Equipment

What size water tank does a villa on Koh Samui need?

The right tank is a buffer against the gaps in your supply — sized from how many people use the water and how long resupply really takes.

June 22, 2026 · 5 min read

Four bottles of well water on a plant-room bench, one sandy, one orange-brown, one clear and one with white scale at the rim, beside a conductivity meter and test strips, with filter housings behind

Equipment

What kind of treatment does your well-water problem point to?

Most villas do not need "a filter". They need the treatment that matches what is actually wrong with their water, and one or two common problems are not filtration problems at all. Start from what you notice, confirm it, and only then look at a category of equipment.

June 19, 2026 · 8 min read

Two drillers lowering a drill rod into the rotary table of a rig at a Koh Samui villa plot, with rock cuttings and muddy water running from the borehole into a settling pit

Drilling

How deep does a well need to be on Koh Samui, and why depth alone does not make a good well

“How deep?” is the first question about any new well, and it hides three different numbers: how far the bore is drilled, where the water stands in it, and where the pump hangs. This guide separates them, explains how the drilled depth is actually decided at the rig, and why a deeper bore is not automatically a better one.

June 15, 2026 · 9 min read

Guides

Groundwater permits in Thailand: what property owners need to know

When a licence is required, who applies, and why a legal well protects you at resale time.

June 1, 2026 · 6 min read

Villa owner in the dry season checking the level indicator on the side of a polyethylene water storage tank, with a parched lawn and the villa wall behind

Water Supply

How to prepare a Koh Samui villa for dry-season water shortages

A villa rarely runs dry because of one thing. The well gives a little less, the house fills up, the pool and garden drink more, and the reserve that looked generous in October is gone by the second week of March. Preparing means knowing those numbers before the season, not discovering them during it.

May 20, 2026 · 9 min read