As threats of future water scarcity mount for Cape Town, gallons upon gallons of water rush from Table Mountain, through the city's belly and into the sea every day.
This was witnessed by a Cape Argus team, who yesterday went underground with an expedition of the Cape Town Partnership, who is working to remedy the situation of the scarce resource going to waste.
Project Reclaim Camissa is one of the partnership's "big ideas" for the development of the central city, and aims to make better use of the city's fresh water sources in a myriad of creative ways.
Camissa project leader Caron von Zeil believes that the city has the potential to once again become self-sustainable, and her vision is to ensure that by 2020, a new civic infrastructure inspired by a deliberate recognition of and respect for the social, cultural and ecological significance of the city's water, will be in place.
Beautiful parks, pedestrian walkways and urban public places will celebrate the waters that link the mountain to the sea, the past to the future, and people to the environment.
But the project is still in its research stage, and funding will determine the pace of future implementation, Von Zeil says.
For now, however, the cool water courses out of sight, where only colonies of cockroaches bear witness to its precious existence.
Yesterday, the roaches had rare company, as Von Zeil and the partnership showed a group of about fifty people how much water the city would have at its disposal if Camissa - the place of sweet waters as Khoi farmers once called the City Bowl - is reclaimed.
We entered the stormwater system through a manhole in upper Oranjezicht, and climbed fugitive-like from a manhole in the Castle of Good Hope grounds two wet kilometres later.
Despite the waivers that were signed and the ambulance parked metres from the open manhole, nervousness only set in once it was explained that guides had a numbered list of manholes we could use as emergency exits in the event of panic attacks.
Sitting crouched in the concrete stormwater pipes while waiting for the rest of the team to descend, boots already filled with water, the precariousness of our position hit home and anxiety threatened to end the excursion before it began.
But fear of later taunts trumped immediate anxiety, and we set off - happily unprepared flashlight-wise - down the system.
Armchair philosophy abounded as we made our way, crouching and slipping, through the racing water.
Historical facts - some more accurate than others - were bandied about and hazard warnings were passed from the team leader down the line.
About a third of the way down the mountain, the subterranean scenery changed.
We could now walk upright, and were surrounded no longer by a concrete structure, but by a facebrick, built canal.
Stalactites started to make their appearance, as did the first cockroach, whose plentiful friends would only be encountered further down the line.
There would be no rats, we were thankfully, and truthfully, assured.
Throughout the walk, blessings were sent to the designers of stormwater systems, as the occasional pool of light and air found its way into the dark.
Occasionally, team leader Dwain Esterhuizen of FO8, an events company that has taken extreme adventure seekers down this particular drain before, would relay our real-world orientation.
That's how we knew when we were under the Gardens shopping centre, or Harrington street, or Roeland street.
Rumour had it that the manhole covers in Roeland street outside parliament had been welded shut.
Some said it was for former US president Bill Clinton's visit, someone else reckoned it had been apartheid head of state PW Botha's doing.
Not much further down the line, things started getting slightly odourous - and old.
We entered the third and last leg of the journey, where the facebrick was replaced by the same stone which had been used to build the castle.
And the tunnel changed shape from its earlier perfect roundness, to a more squished oval shape, built by hand during the earliest days of colonisation.
History enveloped the awed walkers, until at manhole number 14, the light at the end of the tunnel beckoned.
Clambering ungracefully from the manhole onto the grass at the side of the Castle, the cars racing down Darling street took a while to register through the disorientation.
Further up was Table Mountain, from where we earlier surveyed the route we would travel.
Reality slowly returned, and we were back in the future.
Partnership CEO Andrew Boraine said the aim of the stormwater walk had been to get a better understanding of the water system and flow, particularly how it gets from the mountain to the sea under the city.
"The walk convinced me more than ever that Reclaim Camissa is a necessary and viable project for us," he said.