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BWT · Softeners · Reverse Osmosis · Filtration

Water treatment for Marbella & the Costa del Sol

The Costa del Sol has some of the hardest water in Spain. Left untreated, it silently destroys boilers, heat pumps, and appliances — and makes drinking water taste poor. We install water softeners, reverse osmosis systems, and filtration units that protect your property and your health.

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Heating and water system installation Marbella
The Problem

Hard water is costing you more than you think

Water hardness on the Costa del Sol regularly exceeds 400 mg/L — classified as very hard. Every litre passing through your pipes deposits calcium and magnesium salts that accumulate over time as limescale. The result is reduced efficiency in boilers and heat pumps, blocked shower heads, streaked glassware, dry skin, and expensive early replacement of appliances.

A properly specified water treatment system pays for itself — in lower energy bills, extended appliance life, and reduced maintenance costs across the whole property.

  • Limescale build-up reduces boiler efficiency by up to 15% per mm of scale
  • Protects heat pumps, underfloor heating circuits, and solar thermal systems
  • Extends the life of dishwashers, washing machines, and coffee machines
  • Softened water uses less soap, shampoo, and cleaning products

Costa del Sol water hardness — some of the highest in Spain

Marbella, Estepona, Mijas and surrounding areas draw from aquifers in limestone terrain, producing water with hardness levels of 350–500 mg/L (CaCO₃). For context, water above 200 mg/L is classified as hard; above 300 mg/L as very hard. Without a softener, your boiler, heat pump and appliances are accumulating scale every day they run.

25+
Years on the Costa del Sol
400+
mg/L typical local hardness
15%
Efficiency lost per mm of boiler scale
Free
Water test & system survey
The Systems

Three solutions — often used together

Softeners, RO, and filtration each address a different aspect of water quality. The right combination depends on your water supply, property size, and what you want to protect.

Most Popular

Water Softener

An ion exchange water softener removes calcium and magnesium from the supply before it enters your home's pipework. The result is soft water throughout — no limescale, no streaks, noticeably better for skin and hair.

  • Eliminates limescale from all pipework and appliances
  • Protects boilers, heat pumps, and underfloor heating
  • Reduces soap, shampoo, and detergent consumption
  • Extends the life of washing machines and dishwashers
  • Automatic regeneration — minimal ongoing maintenance
Best for Whole-house protection. Installed at the mains entry point — treats all water before it reaches any tap, appliance, or heating circuit.

Reverse Osmosis

A reverse osmosis unit installed under the kitchen sink delivers purified drinking water on demand, removing up to 99% of dissolved solids, nitrates, chlorine, heavy metals, and bacteria. If you currently buy bottled water, RO will pay for itself quickly.

  • Up to 99% reduction in dissolved solids (TDS)
  • Removes chlorine, nitrates, heavy metals, and bacteria
  • Dedicated drinking water tap at the kitchen sink
  • Eliminates ongoing bottled water cost
  • Compact under-sink installation, minimal footprint
Best for Drinking and cooking water. Often combined with a whole-house softener — the softener protects appliances, the RO provides pure drinking water.

Filtration Systems

Sediment and carbon filtration removes suspended particles, chlorine, and odours from the mains supply. Can be installed as a standalone solution or as a pre-filter stage ahead of a softener or RO unit to extend media life and improve output quality.

  • Sediment filters remove sand, rust, and suspended solids
  • Activated carbon removes chlorine and improves taste and odour
  • Multi-stage configurations for higher quality output
  • Extends the life of downstream softeners and RO membranes
  • Simple cartridge replacement — once or twice per year
Best for Properties on well water or with visible sediment. Also used as a pre-treatment stage in any multi-system installation.
Our Brand

BWT — Europe's leading water treatment specialist

BWT (Best Water Technology) is Austria's largest water technology company and the market leader for residential water treatment across Europe. Their product range — from whole-house softeners to under-sink RO units — is engineered for performance, reliability, and minimal ongoing maintenance.

We specify BWT as our primary brand because of the quality of their equipment, the availability of service parts in Spain, and the consistency of their results in hard water conditions like those found across the Costa del Sol.

  • Market leader in residential water softening across Europe
  • Full range: softeners, RO systems, and filtration — single supplier for the whole installation
  • Parts and consumables available in Spain — no long waits for filters or membranes
  • Compact, well-designed units suited to villas, apartments, and small commercial premises
Oasis heating and water system plant room Marbella
Our Process

From water test to working system

We start with a free water test to measure your actual hardness and TDS levels, then recommend the right combination of systems for your property. No guesswork, no upselling — just a solution matched to your water supply.

  1. 1

    Free water test & survey

    We visit the property, test your water hardness and TDS on-site, assess the existing pipework and appliances, and establish what you want to protect.

  2. 2

    System recommendation

    We recommend the right system — or combination of systems — with clear pricing. Softener only, RO only, or a combined installation. You decide.

  3. 3

    Installation

    Our own technicians carry out the full installation — no subcontractors. Softeners typically take half a day; under-sink RO units are done in two to three hours.

  4. 4

    Commissioning & maintenance plan

    We commission the system, test the output, and explain the simple ongoing maintenance — salt replenishment for softeners, annual filter changes for RO. We can handle ongoing maintenance as part of your service contract if preferred.

Water treatment installation process
Is It Right for You?

When water treatment makes the most sense

✓ Good candidates

  • Any property on the Costa del Sol — local water is very hard by default
  • New builds — fit the softener before the heating system is ever exposed to hard water
  • Properties with a heat pump, underfloor heating, or solar thermal — these are particularly sensitive to scale
  • Households buying bottled water — RO will cover the cost in 12–18 months
  • Properties with visible limescale on taps, showers, and glass
  • Anyone on well water — sediment filtration is usually essential

→ Things to consider

  • Softeners require block or granular salt — typically a 25 kg bag every 4–8 weeks depending on water consumption
  • The softener needs a drain connection and a power supply near the mains entry point
  • Softened water is not recommended for watering plants or filling swimming pools — a bypass for outdoor taps is standard
  • RO units produce a small amount of reject water (brine) — usually returned to drain
  • Annual filter and membrane changes are required on RO units — we can include this in a service plan

Areas we cover

Marbella Estepona Benahavís Sotogrande Fuengirola Mijas San Pedro de Alcántara Nueva Andalucía Puerto Banús La Zagaleta

Find out how hard your water really is

We'll visit the property, test your water on-site, and tell you exactly what we recommend — at no cost and with no obligation.

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