Philtration

The house on Kasemsan Soi 3 has been in the Kasemsuwan family for more than a century, designed during the reign of Rama V by the same Italian architects responsible for the Ananta Samakhom Throne Hall. In the late nineteenth century, the patriarch Boonmee Kasemsuwan – better known as Moh Mee – concocted his famous herbal medicine in the basement, distributing it across Bangkok by canal. After he died, the family sealed the chamber.

When Nachapol 'Na' Kasemsuwan, a fourth-generation descendant, decided to open a bar, he went underground. Philtration – from ‘philtre’, meaning potion – occupies that original basement. The concept was not invented so much as excavated.

The entrance requires patience: a heritage compound, a left turn, an antique medicine cabinet, a door that reveals itself only if you know how to look. Inside, the basement is cave-like and warm, lit dimly, with much of the original interior left deliberately intact. A live band plays most nights. The room vibrates slightly with it.

Every drink still carries a mock health claim – a wit inherited from Moh Mee's remedy packaging – but the 2026 menu is the most technically ambitious the bar has produced. The signature Janette Bond's Martini reworks the classic with pomegranate-infused vodka, U-Thai Moh Mee herb, rose vermouth and pomelo-zest gin. Sweet Tears of Mine 2.1 builds on Colonist Spiced Rum, now house-infused with lemongrass and kaffir lime, balanced by Tio Pepe and sharp Granny Smith juice. The Witcher arrives tableside in tamarind-shell smoke, its base a pork fat-washed white rum with more Moh Mee herb and tamarind syrup – the kind of drink that sounds like a provocation until it doesn't.

Newer additions sharpen the programme's identity. Waste Not!, built around lacto-fermented watermelon-skin brine and clarified watermelon juice, began as an environmental principle and ended up one of the most drinkable things on the list. Beneath Earth goes the other way: black truffle, house peach liqueur and truffle balsamic over an ice ball, with a cognac upgrade ladder running from Askaneli 3 Year to XO. Several cocktails now use house-made liqueurs – kaffir lime triple sec, coffee-banana liqueur, peach liqueur – giving the bar a creative depth that off-the-shelf programmes simply cannot replicate.

What separates Philtration from bars that borrow the speakeasy form without earning it is that it has something irreplaceable at its centre: an actual building, an actual story and a family still telling it. The concept was not designed. It was revealed.

2 Kasemsan Soi 3, Wang Mai, Pathum Wan. Open daily, 7pm-2am.