The water monitor.

OK---whileresting , I searched the internet and am convinced this was the creature that was in my chalet bathroom.  I reproduce extracts from the web-site.

Water monitor
The Water monitor, (Varanus salvator) is a large species of monitor lizard capable of growing over 3 meters (9.8 ft) in length, with the average size of most adults at 2.5 meters (8.2 ft) long. Maximum weight of Varanus salvator can be over 75 kg, but most are half that size. Their body is muscular with a long powerful laterally compressed tail. Water monitors are one of the most common monitor lizards found throughout Asia, and range from Sri Lanka, India, Indochina, the Malay Peninsula and various islands of Indonesia, living in areas close to water.
They run fast for their size as they have powerful leg muscles. In fact, they are faster than most of us can run.

Behavior and diet 
Water monitors can be defensive using their tail, claws, and jaws when fighting. They are excellent swimmers, using the raised fin located on their tails to steer through water. Water Monitors are carnivores, and have a wide range of foods. They are known to eat fish, frogs, rodents, birds, crabs, and snakes.[1] They have also been known to eat turtles, as well as young crocodiles and crocodile eggs[4] Like the Komodo Dragon, it will often eat carrion.[1]