« If energy fails for many hours, the water ends everywhere »

The electricity failure to which Portugal watched last month showed some weaknesses and proof that, without light, very little works. Or at least for a long time. One of these examples is water. The sunrise spoke to Joaquim Poças Martins, a water expert, to try to understand how supplies and distribution works and what are the consequences of a blackout.

Many municipalities manage low water and there are companies that make it up. How is this process?
Most municipalities buy water already treated from companies up and the municipalities then distribute. The municipalities have storage reservoirs they give to a maximum day or two days. More than two days nobody has. The time when this time was the water, it was the worst, because at that time the reservoirs are almost always below, after the morning peak, where everyone got up and took a shower. At this time, in many cases, there was enough water for just a few hours of consumption.

And then there is a difference in supply: by pumping or gravity. Do everyone need light?
By gravity it does not need, but this situation is rare, it is almost always necessary and certainly the treatment stations do not work if the energy is below. And almost all buildings above 4 to 5 floors have their own bombs, which do not work without energy either. Therefore, if the energy fails for many hours, water ends everywhere.

Is it a normal situation or should municipalities think about how to generate water so that these situations do not happen again?
The rule is that municipalities have reservoirs for one to two days of consumption, so that the discharge is failed during this period, continue to ensure distribution. But failing the energy for one to two days is very rare, hopefully it does not become fashionable. There may also be a severe malfunction at the treatment plant or a river pollution outbreak, for example a truck with a very dangerous chemical where water is captured to the treatment plant and for some time, until water clean, no water is injected into the municipalities. This is why municipalities must have some reserve capacity that is always around a few hours, desirably, one day or two. Nor can it be much more, because the water would be damaged. Thus, if the supply fails for more than two days, everyone is without water. In systems there are generators, but they are never enough. The power that would be needed to have 100% generators is very large and would force out disproportionate facilities and costs.

Many municipalities have only mobile generators…
But generators do not solve, they do not serve for that. They serve to keep hospitals and some small things work but there are limits. It is not possible that, if it fails the electricity, everything remains normal, this would require a number of generators that is absolutely disproportionate and impossible.

And the reserve estimate has several conditions.
Yes true. But this may have this as a rule: water needs energy to get home to people. It is very rare the situation in which this does not happen, for example when the water source and the treatment plant are high on the mount, above the houses, but it almost never happens. It depends on the sites. But this is really the rule: a some -hour energy failure should not cause supply interruptions, between one and two days, the municipalities that have larger reservoirs can handle, but after two days they are all without water.

To this day we did not have the notion of connection between light and water.
Without electricity there is no water at home either. It is interesting that there are countries where people have reservoirs at home, everyone has a reservoir at home. And then, if the water fails, for a while there are no problems. In many cities in Africa, Asia and Latin America, there is only supply for a few hours a day or even for a few days a week and therefore houses have reservoirs, sometimes for 15 days. Having a small reservoir at home, with a few dozen liters, can be a good idea, but be careful to renew water regularly because it spoils.

Certainly some municipalities took lessons from here…
Yes. At least those municipalities that have been without water will realize why and will see if they can improve anything, in articulation with their company high.

For example, the reservoirs can be managed so that they are never less than 50% or even 75% of the maximum capacity, but this forces to spend more energy: at night the energy is much cheaper but to keep the reservoirs “always on top”, it also has to pump over periods when the energy is more expensive, in fact much more expensive than at night, such as bi-hours that some people have at home. The blackout was a warning, another can come and, as it is almost all -dependent on energy, we all learn that we have to have enough at home for two to three days: money, food, water, flashlights, candles and gas stove. But the likelihood of forgetting what happened is great.