Qanats (or foggaras or khettaras) are of great importance in the history of human settlements, especially in arid areas. Apparently originated in pre-Achaemenid Persia, due to their efficiency they have been spread all over the world, and particularly in the water scarce Mediterranean region.

In modern Greece, the biggest known qanat is found at the outskirts of Thessaloniki. The qanat of Ag. Paraskevi feeding from the rich in water Hortiatis Mountain with the complementary aqueduct has a total length of 20 km approximately. This qanat constitutes an excellent example of the ancient water drainage system, which has strongly influenced the city’s socio-economic organisation. The qanat’s subterranean channels (tunnels), excavated probably during the Roman period, have been used for exploitation and transfer of groundwater from the mountainous terrain to the surface without pumping.

Mount Hortiatis, rich in water since antiquity, has always played an important role in supplying Thessaloniki city and therefore strongly influenced its socio-economic organisation. Actually, throughout Thessaloniki’s long life the city has been depended on the Hortiatis qanat for fresh water supply, as, due to the area geology no other known waterworks method was applicable.

Even if this system performs sustainable supply of fresh water till today, it faces pollution problems from pesticides use, wastewater discharge and building activity in the greater area. In this respect, this case study aims to:

• Make known this monument that is to large extend ignored in our days;
• Call for its protection against pollution, abandonment and other threats; and
• Promote the adoption of such sustainable methods for harvesting water.