Tracing back from the tap, he’s recreated the descent of water, from glaciers down through mineral-rich mountain streams, inside a stack of five interconnected copper urns —what he calls, the Common Man’s Water Filter.

Pouring ground water into the first urn, Laul explains his latest invention.

It’s a five-step process; water passes through each urn in turn, running past natural filters-coconut shell charcoal, marble chips, white sand and a silver coin in the bottommost urn, where the purified water collects.The result is water fit for consumption, which “does wonders for the immune system” according to Laul; the filter has been approved in clinical tests conducted by Development Alternatives.

As I take a sip, Laul asks if I’ve ever tasted anything like it. It certainly tastes different, I say, still thinking of how exactly, when he interjects: “It’s the minerals.”With instructions on how to construct the filter posted onto his website, Laul is determined not to patent his design. “You don’t patent common sense,” he says.

And according to Laul, “if you can’t punch holes into copper urns and fix a tap at the bottom, then you don’t deserve it”.

Those who do are scattered across the globe, from Lucknow to Australia. And consumers include social activist Nafisa Ali and Parimal Rai, chairman of the New Delhi Municipal Council. “I’m not keeping track,” says Laul, estimating around 200 people that he knows use the filter. There are even some trickling through wines and whiskey; it adds a great flavour they report.

And now word is slowly spreading to the target audience—the lowest socio-economic groups—with NGO Shruti Foundation holding workshops with slum dwellers.But one person Laul hasn’t won over is his wife. “She’s the most difficult to convince,” he says with a smile, “she prefers to use the same filters as her friends.”

A company working on an up-market model of the filter, however, with gizmos such as a metre detailing the quantity of minerals in the filtered water or slim line tubes instead of urns, could draw in the sceptical.

“It would make my evening to think people would pay ten times the price for something that shouldn’t cost more than Rs 1,200,” says Laul.