Much of the credit for the creation of these tanks goes to Parakrama Bahu, a 12th century king who declared: "Let not even a drop of rain water go to the sea without benefiting man."
What makes Kandalama special is that on its shores is an extraordinary hotel that has won awards for not only its architectural design but its environmental policies and practices.
Heritance Kandalama was built by Sri Lanka's most illustrious architect, Sir Geoffrey Bawa. His mission at Kandalama was to design a hotel that would settle into its natural environment and in time be almost invisible under a curtain of vegetation.
Enormous rocks from the hill behind the hotel are incorporated into the building which stretches a staggering 1.8 kilometres along the lake shore on seven levels.
Entry to the hotel is through a cleft between the smooth, golden flanks of a giant boulder that also serves as the back wall of the main reception desk.
The hotel is set on pillars so that rain and spring water from the hillside can flow unimpeded into the lake and so that animals too can move about freely.
Infinity edge pools were one of Sir Geoffrey's signature features. The main pool at Kandalama seems to flow seamlessly into the tank beyond. I swam in it at dusk as the lake began to glow with sunset colours and langur monkeys bounded along the pool's lip.
The hotel prides itself on its environmental awareness and has its own resident ornithologist who takes guests on jungle treks and on early morning lake cruises. Even on the way down to the shore we saw golden sunbirds darting through the trees. Out on the lake it was a flurry of avian activity: herons, egrets and storks sat perched in trees or flapped lazily overhead. They were watched imperiously by several pairs of fish eagles.
Sir Geoffrey practised architecture for nearly 40 years, his career being ended by a stroke in 1998. He died in 2003 and is now regarded as one of the most important Asian architects of the 20th century.
I am sure that if he could see how his beautiful hotel is now, almost totally engulfed in plants that are teeming with birdlife and monkeys, he'd be delighted.
Although it's tempting just to stay at the hotel, watch the birds, swim in the pool and indulge in the food (I became happily addicted to having a chef prepare me a hot crispy dosa rolled up with potato masala each morning), Kandalama is also at the heart of Sri Lanka's cultural triangle. Within this are several World Heritage Sites (and some which are on Unesco's tentative list for consideration as heritage sites), which include some stunning examples of Buddhist art.
If you are approaching Kandalama from the Sri Lankan capital of Colombo, one of the first sites you will encounter is the rock fortress of Yapahuwa. During the 13th century a Sinhalese king, on the run from invading Indian armies, set up his capital here on top of a 90-metre-high granite outcrop.
Each time the kings moved their capital, they took with them Sri Lanka's most treasured relic, the Sacred Tooth of the Buddha and the Bo tree (under which the Buddha achieved enlightenment).
Today, little remains of this short-lived capital apart from a beautiful stone staircase which would have once led to the king's palace and temples.
However the staircase is worth a visit on its own. It's guarded by two stone lions and is decorated with carvings of musicians and dancers. It's extremely steep - in fact almost vertical - but the reward for puffing to the top in the tropical heat is the view over the plains below and being able to study the amazingly well preserved carvings on the way up.
It's also good training for the climb to the top of the much better known and more spectacular rock fortress of Sirigiya. More about that next time...
