Costa del Sol Water Supply Doubles But Hard Water Remains
The Costa del Sol is getting a major water supply boost, but the white crust on taps, shower screens and pool equipment is not going anywhere by itself.
Acosol has revived the €50 million El Verde project, a major upgrade to a plant that has been operating since 1972. According to SUR on 10/10/2026, the project aims to raise capacity from 1.500 L/s to 4.600 L/s, helping cover demand for around 2 million people in summer.
That is good news for homes, urbanisations, hotels, restaurants and anyone who remembers water pressure drops or summer restrictions. More treated water means a stronger safety margin in August.
But there is one detail many people will miss.
The El Verde upgrade improves supply. It does not remove hardness.
The El Verde project should ease summer supply pressure
The Costa del Sol has a difficult water pattern. Demand rises sharply in summer, especially across the western coast, when resident populations, tourism, gardens, pools and hospitality all place pressure on the network at the same time.
El Verde already plays a central role. The plant treats around 77% of the water used in the area, so increasing its capacity is a serious infrastructure move.
The reported jump is large:
Current capacity | Planned capacity | What it means |
1.500 L/s | 4.600 L/s | More than triple the treatment capacity at El Verde |
Built in 1972 | Revived €50 million project | A major update to a key part of the network |
Supports peak summer demand | Around 2 million people in summer | Better protection during the highest-use months |
For anyone living between Marbella, Benahavís, Estepona and surrounding residential areas, this matters. It should reduce the chance of August shortages, pressure drops and emergency cuts.
That part is worth welcoming.
Water availability has become one of the most sensitive issues on the coast. A stronger treatment plant gives Acosol more room to manage demand. It also helps when the region faces dry years, reservoir strain or sudden population spikes.
But a bigger supply does not mean a softer supply.
Hard water is a different problem
Hardness comes mainly from dissolved minerals, especially calcium and magnesium. On the Costa del Sol, much of that mineral content comes from water passing through limestone areas, including the Sierra Blanca system.
That is why hard water is not simply a treatment plant issue.
El Verde can treat water to make it suitable for supply, but standard municipal treatment does not normally remove the minerals that create limescale. The plant can improve capacity, quality control and reliability, yet still send water into the network with high mineral content.
That is the key distinction:
Supply capacity
Hardness
How much water the system can treat and deliver
How much dissolved mineral content remains in the water
Acosol’s upgrade addresses the first issue. It does not solve the second.
That means areas already known for hard water will still have hard water after the project. The symptoms will stay familiar:
White marks on taps and shower screens
Scale build-up inside kettles and coffee machines
Reduced efficiency in boilers and heating systems
Blocked shower heads and aerators
More cleaning around glass, chrome and tiles
Stress on appliances that heat water
Dull laundry and stiff towels in some homes
This is where people often misunderstand public Water treatment. Municipal treatment and domestic softening are not the same thing. One protects the public supply. The other changes the water inside a home or building.
Why La Zagaleta and El Madroñal will still see very hard water
Some of the highest readings in the area are found in hillside residential zones, especially where the local geology contributes heavily to mineral content.
Based on recent testing and known local patterns, La Zagaleta and El Madroñal remain in the 400 to 600 mg/L range. That is very hard water.
Estepona is often lower, but still hard, commonly around 300 to 400 mg/L.
These levels are not caused by the age of El Verde. They are linked to the natural mineral profile of the water source and the limestone it moves through before it reaches the network.
In practical terms, this means a property in El Madroñal can receive reliable water after the upgrade, but still see scale forming quickly on:
Shower glass
Marble and stone surfaces near taps
Pool fill valves and irrigation parts
Underfloor heating circuits
Domestic hot water systems
Coffee machines, steam ovens and dishwashers
At 400 to 600 mg/L, hard water is not a small inconvenience. It becomes a maintenance issue.
The higher the hardness, the quicker scale forms when water is heated or left to evaporate. That is why hot water systems, kitchens and bathrooms show the worst signs. The same water that looks clear from the tap can leave a heavy mineral deposit once it dries.
What a 580 mg/L reading means in a real home
This week, a test in El Madroñal showed 580 mg/L.
That reading was taken before and after the El Verde news. The number did not change because the announcement does not alter the mineral content currently arriving at the property.
After a domestic softener, the same property tested at 90 mg/L.
That change matters. It shows the difference between public supply treatment and in-home hardness reduction.
A reading of 580 mg/L means the water contains a high level of hardness minerals. It will usually create visible limescale quickly, especially where water is heated, sprayed or allowed to dry on a surface.
A reading around 90 mg/L is much easier to live with. It does not remove every mineral from the water, but it greatly reduces the scale load inside the home.
For many properties, that difference can be seen in daily use:
Before softening | After softening |
580 mg/L in El Madroñal test | 90 mg/L after the softener |
Fast scale build-up | Much slower scale build-up |
More frequent descaling | Less frequent descaling |
Higher stress on appliances | Better protection for hot water systems |
Marks on glass and chrome | Easier cleaning |
The aim is not to make water “perfect”. The aim is to bring hardness down to a level that protects the property and makes daily maintenance easier.
The supply upgrade and hardness issue can both be true
People often hear “water treatment upgrade” and assume all water quality problems will improve. That is understandable, but it mixes two separate subjects.
A larger treatment plant can help with:
Capacity
Reliability
Peak demand
Network resilience
Summer supply pressure
It does not automatically help with:
Limescale
Hardness minerals
Calcium deposits
Scale in boilers and appliances
Mineral marks on surfaces
This is why the El Verde project is good news, but not a limescale solution.
In fact, better supply can make the hardness issue more visible in some homes. If water use increases during summer because restrictions ease, then more hard water moves through showers, boilers, irrigation systems and pool equipment. More usage can mean more scale deposits, even if the water itself has not changed.
That is especially relevant for larger villas, rental properties and homes with several bathrooms. A single household can push a lot of hard water through its systems during July and August.
Why exact testing matters more than guessing by town
Hardness changes by area, and sometimes by urbanisation. One part of the coast can sit at 300 mg/L while another nearby property tests far higher.
That is why broad town-level assumptions are not enough.
For example, “Marbella water” is not one single number. A beachside apartment, a Nueva Andalucía villa and a hillside property near Benahavís may not receive water with the same hardness profile. Pipework, supply zones and source blending can all affect the final reading at the tap.
The same applies across:
La Zagaleta
El Madroñal
La Reserva
Almenara
Estepona
Benahavís
Marbella hillside areas
Testing gives a clear number in mg/L. Once that number is known, it becomes much easier to choose the right system size and understand what kind of improvement to expect.
A proper test should ideally use water from the property itself, not a general estimate from a map. The kitchen cold tap is usually a useful starting point, but other points may also be checked depending on the home’s plumbing.
What homeowners should watch after the El Verde upgrade
The El Verde project should be followed closely, especially as the Costa del Sol continues to deal with high seasonal demand. More capacity is a major step for the region.
Still, for property owners, the next practical question is simple.
Will the water inside the home be less hard?
Based on the nature of the project, the answer is no. Not unless hardness removal is added somewhere else in the system or at the property.
After the upgrade, look for the same signs you see now:
Scale returning quickly after cleaning
Shower heads losing pressure
Kettles forming white flakes
Coffee machines asking for descaling often
White crust around taps and valves
Cloudy marks on glassware
Boiler or hot water maintenance linked to scale
If these continue, the issue is not poor cleaning or a faulty appliance. It is the mineral load in the water.
For costa del sol water treatment decisions, the most useful first step is still a simple hardness test. It gives a number, not a guess.
The takeaway for the western Costa del Sol
Acosol’s revived El Verde project is a major supply story. Raising capacity from 1.500 L/s to 4.600 L/s should help protect the Costa del Sol during peak summer demand and reduce the risk of August cuts.
That is the good news.
The practical limit is just as clear. El Verde treats a large share of the area’s water, but it does not remove limescale. Areas such as La Zagaleta and El Madroñal can still sit around 400 to 600 mg/L. Estepona can still sit around 300 to 400 mg/L. The minerals come from the water’s natural path through limestone, not simply from the plant.
The recent El Madroñal test says it plainly: 580 mg/L before softening, 90 mg/L after softening.
If you want to know the exact hardness in La Zagaleta, La Reserva, Almenara or nearby areas, we provide free tests. Get it touch with us and get the mg/L reading for your property.
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