Sourced

 

Heading away from the Georgian capital, Sascha's next destination is the small town of Borjomi. 
Surrounded by protected nature reserves (Georgia's largest national park of Borjomi Kharagauli), Sascha introduces the town as such:

'Borjomi is famous for its carbonized mineral waters that in the past were distributed in whole Russia. Today, the City of Borjomi is a good starting point for hikes in the Borjomi National Park, but no hot springs there'.

It seems that Borjomi is synonymous with mineral water. 

The wikipedia link above notes that from the 19th century taking the waters here resulted in the town coming into existence.  
Communism seems to only have changed the soakers provenance: from the aristocracy to the new elite.

Bottling the mineral waters has both enhanced the town's reputation as well helped the local labour force. 

Advice

However the (hot) spring itself is located some way from the town, which despite the experience of the soak itself does enhance the overall experience of being in nature. 

Sascha:

'According to the [Park] Ranger, the only hot spring is located in the Borjomi Village park. You can either start the walk from Borjomi or take the car up to Sadgeri and walk down the hill to the river (around a 15 minutes walk)'. 

But is it hot? Sascha:

'The hot spring is in reality only a 28°C warm spring (at source), the pool water has only 26°C'. 

The experience. Sascha:

'The surrounding is beautiful but by far too overcrowded. It is therefore advisable to go there in the morning. It has more the character of a public swimming pool. An entrance fee of 5 Lari needs to be paid'.

There are more experiences to be had from Borjomi, much in the same vein: a fair walk to the rehabilitated pools which tend to be quite packed. Note that the changes to the pool and settings are of recent years, so if seeking to emulate an experience of say 5 years back: it's not going to happen.

Tripadvisor refers to this as Borjomi Sulfur Pools or more frequently Borjomi Central Park:

'Useful tip: visit sulfur bath early in a morning - 06:00-07:00, and you will enjoy it with only few people, after 10:00 - it will be disaster'.