How did District VII. get involved in the Urban Rain project?

The LIFE in RUNOFF project examines the possibilities of mitigating and preventing the damage caused by flash floods caused by climate change in three different catchment areas and three different topographic and built-up districts.

Erzsébetváros, as a flat and densely built-up inner-city district, is an excellent complement to the much less built-up and differently shaped XII. and XVIII. districts. In terms of sewage and stormwater drainage, it is part of the catchment area of the Ferencváros Pumping Station, which discharges the incoming water to the Central Sewage Treatment Plant.

Why the Klauzál Square Hall?

The site was selected by examining the buildings in the district and consulting with experts (Budapest University of Technology and Trinity Enviro Ltd.). The main advantage of the Market Hall is that its roof surface is much larger than that of other buildings, so rainwater harvesting can have the greatest impact, and large volumes of rainwater can be collected and used more efficiently due to economies of scale. An additional advantage is that the investment does not require the rebuilding of the utility network (in the case of other project elements, utilities can frustrate or make construction more expensive (e.g. the planned investment of the Hegyvidék Municipality of Budapest District XII, which involves a significant replacement of utilities at a cost of EUR 100 million). The storage and use of rainwater collected in a separated system from the roof of the Klauzál Square Market Hall can provide guidance for the partial storage and use of rainwater in what are surely many similar buildings in Budapest.

Why is it important to delay sudden rainfall before it enters the sewer system?

Flash floods in the city are usually caused by a sudden downpour of rainfall, which can’t be drained by the sewer system because it is not designed to handle the same amount of rainfall.

In addition to flooding, flash floods can damage public areas and utilities and lead to inefficient wastewater treatment, not only during the rainy season, but can disrupt the biological functioning of the treatment plant for weeks. The storage of rainwater collected from large roof surfaces reduces the load on the combined sewer system and the use of piped drinking water during the dry period following heavy rainfall.

What happens to the collected rainwater?

After multiple (mechanical, chemical) cleaning, the rainwater is pumped  to the Erzsébetváros Kft. into sprinkler trucks, which are then used to water the surrounding green areas. An overflow at the top of the tank ensures that when it fills up, the excess is discharged into the drain. So in effect, the load on the canal is reduced by the amount of water stored there.

How much water is a tank of water enough for?

The sprinkler trucks have a capacity of one cubic metre, so the tank of almost 60 cubic metres is enough for 60 rounds. The car is filled up about six times a day, meaning that the tank can provide about 10 days’ worth of rainwater for drinking during a drought.

How much potable water can be replaced per year with the rainwater harvesting tank?

The tank is located on half of the roof of the Market Hall and on Klauzál tér 11. It collects water from the roofs of about 1750 m² of the building. For a roof surface of this size, about. 850-1000 m³ of rainfall. However, the reservoir will be able to store less water than this, because if rainfall exceeds 35 mm, the reservoir will fill up and the excess will be discharged into the sewer. Furthermore, as there is no irrigation in winter, up to 35 mm of the winter rainfall can be used. One of the aims of the project is to find out how much rainwater can be used in practice with such a tank.

How long does it take to recoup your investment?

The main objective of the project, and therefore of the investment, is to examine ways to reduce the problems caused by the increasing intensity of precipitation in Budapest due to climate change – flooding damage, damage to public utilities, wastewater treatment problems – and to explore the possibilities of storing and using precipitation in the spirit of the “sponge city” concept. The experience gained from the project could be used to develop a system in Budapest and elsewhere that could help avoid the billions of euros of damage listed above, and help Budapest meet the challenges of increasingly extreme rainfall patterns by harnessing rainwater. This means that the project can pay for itself in the long term and at the Budapest (EU) level.

How much energy do pumps use each year?

Moving one m³ of water is about. requires 0.1-0.15 kWh per hour of energy, so at 1000 m³ approx. can be expected to consume 100-150 kWh per hour of energy per year. The delivery of the same amount of water from the coastal filtration wells through the reservoirs to the hydrants is approx. It requires 3-4 times as much energy. If, for example, water from the larger reservoir or surface water body 3-5 km away were to be transported to Erzsébetváros by small tanker trucks, it would cost about. would require 30-70 times as much energy.

Why didn't the municipality apply for support for the use of water-saving devices by the public?

The LIFE programme supports systemic, long-term, innovative and ecological projects. The LIFE pilot projects aim, among other things, to test methods that would not be worth implementing without funding at present (e.g. for economic reasons), but which could be very important in the future because of climate change and could be applied more effectively based on the project experience. Support for household water saving devices can only be a small part of the project budget. This is also the case in the LIFE UrbanEnergy project: condominiums can apply for 300 litre rainwater collection containers. The support for devices that can be used directly to save drinking water is not in line with the objectives of the project and has therefore not been included.