Gold standard for utility performance

Budapest’s first – DN 500 cast iron – water line was laid down in Nádor Street in 1869 and it connected the temporarily waterworks, which was built on the current location of the Parliament, with the Kőbánya reservoir. The water network was about 23 km long back then, and now it is a 5,350 km long, so-called “depressed” network. The Budapest Waterworks’ pipeline network – due to the built-in locks, it can be divided into sections of different length – is also connected to the systems of other waterworks. As our company produces several times more as the demand, we also give high-quality water to other waterworks.

Construction

Development and construction of the water pipe system is a highly complex and laborious process. During installation or exchange of old pipelines it may be difficult to adapt to other utility lines (pipelines, wires), which must be carried out in accordance with strict regulations. It also requires a great deal of effort during the construction works to minimize disruption in the traffic of the city and ensure the uninterrupted water supply for our consumers.

In addition to the artificial obstacles, environmental ones must also be taken into account, such as topography of the given surface. In the hilly areas, the problem is among others that the soil layers constantly move, so connections of the pipeline might slide apart. In these cases – increasing the load capacity – we use pull-safe connections. In case of inadequate soil, the solution is the complete soil replacement. Another difficulty is the clay soil in Buda which due to its waterproof properties would continuously corrode our pipelines. We solve this problem by using gravel ballast and we use special coated pipes to avoid the harmful effects of the aggressive springs.

Pipe types then and now

The range of materials used in the beginning of our development has been significantly expanded over the years, so we can now install more and more pipe types into our network. In the beginning we used cast iron in our so-called depressed network, but today we use ductile cast iron instead. During troubleshooting – in reasonable cases – we still use normal cast iron pipes of the same quality. Lifetime of the pipes has increased due to the applied protective coating. Load of the pipe (10, 16 bar or even higher pressure) is determined during the manufacturing and waterworks companies just like us can choose the right one in accordance with their needs. Budapest Waterworks uses today ductile cast iron or high-density polyethylene pipes when carrying out reconstruction or expansion works.

Pipe types used by Budapest Waterworks

Budapest Waterworks used the following pipe types for the construction of Budapest’s water supply network during its history:

  • Cast iron: graphite sheet casting made with conventional casting technology
  • Ductile cast iron: coated cast pipe made from graphite, formed into a sphere by adding magnesium
  • Asbestos: pipe made with cement mortar pipe rolling technology
  • HDPE: high-density polyethylene pipe
  • PVC: plastic pipe
  • Sentab: pre-stressed reinforced concrete pipe
  • Hobas: fiberglass pipe
  • Steel pipe

Today we only use the most modern materials for network expansions, such as ductile cast iron and HDPE.

Water pressure in the pipeline

Budapest’s water network is divided into pressure zones. The reason is the level differences: since we deliver the required service to each point of the network – if possible –, areas on higher locations require higher pressure. The pressure of the zones varies between 1.5 and 17 bar.

Safety of our pipes

In addition to continuously monitoring and maintaining water quality, our Company is highly careful in the safety issues of the water supply that cannot be separated from the former. In the following, we will answer a few frequent and important questions regarding the safety of the water supply.

Prevention and protection against contamination

  • Can wastewater get into the pipeline system through the underground sections?

No, because the path of the two water utilities (water, sewage) is different. The sewage is located in the axis of the road, while the water pipe is running under one side of it. The operating pressure in the water pipe is at least 1.5 bar, thus nothing can get into it from a smaller pressure medium.

  • Is it possible to contaminate water pipes from the consumer side?

No. If we lock out a pipe in case of a pipe burst, although it is possible to have back flow into the network, but after repair the pipe section is cleaned with localised disinfection and rinsing, thus network contamination will not occur.

Physical exposures

  • Can the pipeline be punctured?

Puncture can occur on steel pipes or – in case of so-called pitting corrosion – on cast iron pipes. We use steel pipes for the pipelines running on bridges, since they are lighter than other pipes and they are damaged with punctures and not with shell burst, thus they do not cause damage to the bridge structure.

  • How do pipes “age”, are the old pipes dangerous?

Iron based pipes corrode, in case of cement based pipes the cement is leached out over time, and the plastic based pipes will get old. These processes may result in the thinning of the pipe wall which can lead to pipe burst. This is more likely to occur in older pipe sections, but older pipes are not dangerous, in fact the material of some of them is excellent.

  • How can the underground lines be controlled and checked?

We perform state surveys regularly for which we have two available methods: destructive structural and non-destructive examination. On one hand state of the pipes evaluated based on the results examination of samples taken during certain pipe bursts on the other hand following the excavation we carry out corrosion measurement on the exterior surface of metal pipes and also examine the pipe’s environment. With the help of this data we determine whether reconstruction is needed or if it is not justified we identify the additional uptime of the pipeline. Beyond these examinations we perform water loss analysis which covers all the network failures and searches for failures not visible from the surface.

  • Is the water network earthquake-proof?

Since earthquakes have a greater effect on higher structures, therefore, they do not pose any significant hazard to the network. Layer break may cause bigger problems, since in this case cross break may occur on the surface of the pipes.