An Aljibe or Underground Water Cistern

The majority of Mexico is not served by pressurized water systems, requiring some ingenuity to regulate the water pressure in your home. 

On our way to Zacatecas two weeks ago, one particular view from our bus gave us a view of the roofs of a housing development. I noticed on every roof was a black, round cylinder called a tinaco. You'll notice that most houses have a tinaco on the roof. I asked a number of expats how the system works. Few could tell me.

Here's how it works. The city delivers water two or three hours a day to each house. In order to have water whenever it is needed, each house has an aljibe or underground water cistern. The aljibe has a float that shuts off intake when it is full. Then a pump sends the water to the tinaco on the roof and it has a float that shuts off intake when full. The system is now pressurized and showers, sinks, water heater, and toilets can draw on the water from the roof. It is gravity fed and that's why we have pressure when we take a shower. If power fails, as it can here, we still have water from the roof.

Sometimes you will see the tinaco on stilts, to give additional force of gravity to an upstairs shower.

Every house has an aljibe. Our house on Umaran had a had a cistern in the guest bedroom. It was just a cover in the floor by the bed. Here on Huertas, our cistern is off the terrace outside the kitchen, near the BBQ.