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Hydro 4 Mykonos

HYDRO4 is a smart residential water management system located in the village of Ano Mera in Mykonos Island. In this site, rainwater, stormwater and surface runoffs are collected and stored into buffering tanks, in order to recharge the aquifer during the wet season, and to be recovered during the dry season. Stormwater is collected through a hybrid bioswale system, rainwater from the 400 m2 available rooftops and surface runoffs from 350 m2 residential yards.

A small part of the water is upgraded to potentially potable water quality standards, using the slow sand filtration process coupled with disinfection.

The majority of water is used for non-potable domestic uses and the irrigation of 0.2 ha lavender using precision irrigation and online monitoring of the water quality. Lavender was chosen to produce high added value essential oil.

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Level of operation

Household – Residency

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Types of water treatment


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By products

Reclaimed water for irrigation, potable water, herbs, essentials oils

Read more about HYDRO4

The systems consist of three subsystems:

  1. Subsystem: Residential Rainwater Harvesting system
  2. Subsystem: Slow Sand Filtration (SSF) system
  3. Subsystem: Aquifer Storage & Recovery (ASR) system

Subsystem1 collects the rainwater from house roofs. The rainwater is harvested from about 438 m2 of residential roofs collected through a piping system in a water storage tank of 70m3. The water is reused for domestic non-potable purposes, e.g., washing, flushing toilets, etc.

Subsystem 2 refers to the Slow Sand Filter (SSF), which is a water purification system composed of a sand-bed system which through biological, physical, chemical, and mechanical processes purifies the water to potentially potable level.

In Subsystem 3 the rainwater is collected from two sources: (1) surface runoff and (2) bioswale system. The latter is an open-channel linear drainage system with geomembrane and geotextile that collects and partially treats storm water, and prevents the lavender crop from flooding, as the storm water originating from nearby upstream properties often floods the site, preventing the field from growing crops.

During the wet period, the recovered water of this subsystem is transferred and collected in an open tank and the excess water is stored in the artificial recharge location (AR), where a new well has been constructed to store water in the subsurface. The stored water, collected from both systems described above, is used during the summer period for the irrigation of lavender.

Construction Phase

In the first 18 months of the project, a technical visit took place to the site (September 2018), to obtain a visual perception of the potential solutions to be implemented in the respective systems.

Additionally, a field work visit took place (November-December 2018) to conduct geological and geophysical non-destructive surveys, as well as topographical measurements.

At the same period, regional and local climate data were collected and a review of the existing literature concerning the geological, tectonic and hydrological conditions of Cyclades and especially of Mykonos Island was performed.

After the processing of the data from the surveys and site visits the design of the systems were developed.

Another field visit was organized to the HYDRO4 system (June 2019) to perform a series of field experiments and provide a thorough understanding of the hydraulic behavior of the aquifer selected to act as the buffer for water storage.

Most of the construction works in HYDRO4 were completed by December 2019. The design of the bioswale system was already finished and its construction was completed in October 2020.

To monitor the system, sensors measuring the water level and water quality were installed in the tanks and the well (industrial sensors, piezometric sensors and low-cost solar sensors). Moreover, a PLC automation and monitoring system was designed to enable controlling and automation capabilities.

Additionally, an autonomous data collection system has been installed that is designed for the monitoring the aquifer storage. This system collects data for a long period and after the hydrogeological study, optimization actions will take place to increase water management efficiency (pumping, irrigation, AR, etc).

Operational Phase

The start-up of HYDRO4 was conducted in October 2020. During the winter period of 2020-2021, rainwater was collected in Tanks 1 and 2, for domestic and irrigation purposes respectively.

During the current winter period of 2021-2022, the bioswale system is fully operational and up to now 250m3 of rainwater / stormwater have been collected.

In order to monitor all the subsystems in HYDRO4 and enable controlling and automating capabilities, a PLC system with online (industrial and low-cost) equipment has been installed.

More specifically, water quantity is monitored through ultrasonic level meters installed in the tanks and pressure level meters in the wells. For quality monitoring, we have used both online industrial sensors and low-cost sensors (conductivity, pH, T, turbidity).

In addition, a meteorological station installed on the site is used to collect data. In parallel with the online quantity and quality monitoring, sampling campaigns are running since October 2020 to ensure via the analysis of further parameters the smooth operation of the systems and the high quality of the reclaimed water.


  • Decentralised solution to increase water supply
  • Production of drinking water
  • Aquifer recharge to reduce saltwater intrusion


  • 10 > m³ /year drinking water
  • 200 m³ /year water stored in aquifer
  • 1000 kg/year lavender
  • 0.2 ha irrigated


250 >m³/year rainwater harvested
250 €/m³ harvested water