Summary
Summary
Domestic rainwater harvesting in Malta is the long-running Alter Aqua programme. Launched in 2011 in Gozo by GWP-Med with national partners, Alter Aqua installed and reinstated RWH in public buildings - first four Gozo schools for toilet flushing, plus additional school and farm systems - and a greywater unit at Gozo Stadium; it then expanded to Malta. By late 2024 the programme restored historic cisterns (e.g., Birgu) and launched a Reservoir Trail. In 2025 the new “Alter Aqua RECAP” phase adds a focus on domestic greywater recycling. EWA reports the programme now replenishes ~20 million L/year.
Malta’s policy context is distinctive: all buildings must incorporate a rainwater cistern, with sizing/drainage rules in Technical Document F; the 2024 Green Stormwater Infrastructure Manual links building guidance to practical use. A national Domestic Cisterns Restoration Scheme administered by the regulator (REWS) supports household upgrades and has been extended to 31 Dec 2025.
Overall, Malta pairs a deep cistern heritage with modern retrofits, incentives and education ; making RWH effective for non-potable uses and strengthening water resilience on a scarce island setting.
Photo gallery
Overview
Year of issue
2025
Project
NWRM
Implementation status
Ongoing
Contact
Elia Desmot, OIEau
Location of the project
This project covers the whole Island of Malta in the Mediterranean sea.
Country
Malta
NUTS2 Code
Malta
Sponge measures implemented in the case study
Rainwater Harvesting
Objectives
Programme aim (Alter Aqua, launched 2011): help Malta combat water scarcity and raise awareness on sustainable water use, through non-conventional water resources including domestic RWH.
In Gozo island : install 4 new RWH systems in 4 public schools (for toilet flushing) and reinstate 5 existing systems in 3 schools and the Experimental Farm (flushing/irrigation). A greywater unit was also installed at Gozo Stadium (programme bundle). These quantify the initial roll-out relevant to the case’s “domestic/ building” scope.
In Gozo island : install 4 new RWH systems in 4 public schools (for toilet flushing) and reinstate 5 existing systems in 3 schools and the Experimental Farm (flushing/irrigation). A greywater unit was also installed at Gozo Stadium (programme bundle). These quantify the initial roll-out relevant to the case’s “domestic/ building” scope.
Involved partners
| Authority type | Authority name | Authority role | Comments | Authority responsibility |
|---|---|---|---|---|
| Research institute / University | Global Water Partnership – Mediterranean | Initiation of the measure | Programme lead/implementer; coordination, demo installations, capacity building and awareness. | Responsible |
| Other | The Coca-Cola Foundation / Coca-Cola Malta & General Soft Drinks Co. Ltd | Financing | Primary financier (Phase I) | Supporting |
| National water authority | Energy & Water Agency (EWA) | Other | National partner since 2014; supports/hosts activities; communicates results and later phases. | Responsible |
| Other | Education partners: MIO-ECSDE / MEdIES, Nature Trust Malta, EkoSkola | Other | Educational materials, teacher training, youth engagement. | Supporting |
| Other | Schools | Other | Site owners/operators for school RWH; students involved in monitoring water-use impacts at school level. | Responsible |
Site Information
Climate Zone
Warm temperate dry
Precipitation
600.00 mm
Temperature (°C)
18.00 °C
Elevation range
114 m
Groundwater level
Sea Level aquifer, with quantitative assessment based on water balance and issues linked to abstraction; overall groundwater management objectives remain to reach good status.
Vegetation class
Mediterranean shrubland types such as garrigue/maquis
WFD Ecological status
Good
WFD Chemical status
Good
Water quality status
National documents repeatedly flag saline intrusion and nitrate as key pressures on several groundwater bodies
Design and Implementation
Project scale
Large
Project scale specifications
The Alter Aqua project is country-wide.
Constraints
The socio-economic costs of a lack of water sources is already bearing on the domestic, industrial,
agriculture and tourism sectors of the economy.
agriculture and tourism sectors of the economy.
Favourable preconditions
In view of this, domestic rainwater harvesting would be a means of obtaining a secure
freshwater supply
freshwater supply
Financing
Total cost
1091014.00 €
Compensations
No
Policy and Governance
Policy description
Malta has very limited freshwater and depends heavily on desalination; securing water availability is a national priority. The Gozo domestic RWH case sits in this context, targeting water scarcity by substituting potable supply with harvested rainwater for non-potable uses. Under the Water Framework Directive, Malta’s RBMP identifies significant pressures on groundwater, especially over-abstraction leading to seawater intrusion (quantitative pressure with qualitative consequences) and nitrate pollution. Domestic RWH is promoted as a demand-reduction and storage measure; the RBMP Measure 027 explicitly supports restoration/use of domestic rainwater systems.
Land ownership
Programme context shows RWH reinstated in public buildings
Policy targets
Increase Water Storage
Runoff control
Oher Societal Benefits
Part of a wider plan
No
Public consultation
No
Has contractual arrangements
No
Impacts and Monitoring
Maintenance
Maintenance requirements
Maintenance is handled by the site owner (e.g., the school/building) and appointed contractors under Alter Aqua/EWA oversight, with a stated 24-month warranty for the installed works.
Impact Assessment Methodology
Performance impact assessment method
Laboratory
Socio-economic Impacts
Direct benefits
Improved access to water, increased water storage
Alter Aqua benefited >70,000 people (awareness, access to non-potable water) and continues expanding; quantified ~20 million L/year savings.
National incentive (Domestic Cisterns Restoration Scheme) uptake shows thousands of household beneficiaries (e.g., 5,292 in 2015–2016), indicating broad socio-economic reach of domestic RWH beyond this single site.
Alter Aqua benefited >70,000 people (awareness, access to non-potable water) and continues expanding; quantified ~20 million L/year savings.
National incentive (Domestic Cisterns Restoration Scheme) uptake shows thousands of household beneficiaries (e.g., 5,292 in 2015–2016), indicating broad socio-economic reach of domestic RWH beyond this single site.
Biophysical impacts: Hydrology
Information on retained water
Programme-level evidence: ~20 million L/year of water replenished/saved through Alter Aqua installations.
Biophysical impacts: Biodiversity
Improved biodiversity
No
Biophysical impacts: Water & Soil Quality
Information on water quality overall
Only water quantity is impacted
Biophysical impacts: Others
Ecosystem impact climate regulation
No specific impact
Information on ecosystem impact climate regulation
No specific action on water cycle
Lessons Learned
Key lessons
A multi-phase, public–private programme can keep small, building-scale RWH relevant and scalable. In Malta, GWP-Med with EWA and The Coca-Cola Foundation sustained works over >10 years, reporting ~19–20 million litres saved annually and tens of thousands reached.
Reviving historic infrastructure works—if you pair restoration with present-day uses and outreach. Birgu’s reservoirs were rehabilitated (including heavy cleaning) and then showcased via a 12-stop Reservoir Trail, turning heritage into operational storage and public engagement.
Policy and incentives matter. A legal baseline requires cisterns in all buildings (Technical Document F), and RBMP measures and REWS grants support domestic systems—evidence that regulation plus funding accelerates uptake.
Robust site-level monitoring data are not always available. The NWRM fiche for this Gozo case reports no monitoring, limiting quantified biophysical evidence at site scale even as programme-wide numbers exist.
Scaling beyond RWH to greywater reuse still faces obstacles; the current Alter Aqua RECAP phase is explicitly designed to remove barriers and embed solutions into policy.
Reviving historic infrastructure works—if you pair restoration with present-day uses and outreach. Birgu’s reservoirs were rehabilitated (including heavy cleaning) and then showcased via a 12-stop Reservoir Trail, turning heritage into operational storage and public engagement.
Policy and incentives matter. A legal baseline requires cisterns in all buildings (Technical Document F), and RBMP measures and REWS grants support domestic systems—evidence that regulation plus funding accelerates uptake.
Robust site-level monitoring data are not always available. The NWRM fiche for this Gozo case reports no monitoring, limiting quantified biophysical evidence at site scale even as programme-wide numbers exist.
Scaling beyond RWH to greywater reuse still faces obstacles; the current Alter Aqua RECAP phase is explicitly designed to remove barriers and embed solutions into policy.
Drivers
| Driver type | Driver role | Comments |
|---|---|---|
| Legal obligations | Main driver | Clear legal requirement for rainwater cisterns in buildings |
Success factors
| Success factor type | Success factor role | Comments |
|---|---|---|
| Successful coordination between authorities | Main factor | Long-term partnership (GWP-Med, EWA, Coca-Cola Foundation/GSD) with successive phases. |
| Financing possibilities | Main factor | Public funding incentives for household cistern restoration (REWS scheme, extended to 2025). |
| Communication activities | Main factor | Productive reuse of heritage reservoirs plus strong public engagement (Reservoir Trail). |
Transferability
Highly transferable where building codes support/require cisterns and grants fund retrofits. Success depends on strict “second-class water” separation, simple O&M, and user engagement. Take care with water-quality safeguards, plan monitoring of actual savings, and budget for legacy-tank restoration, which can require heavy cleaning and structural repairs.
Sources
Sources