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Questions and Answers

Sofiyska Voda has a high-tech laboratory testing complex, which monitors the water indicators and controls the compliance with the standards for the quality of the potable water that we supply to our customers and the wastewater, which is returned to nature after treatment. 

In 2017 the LTC obtained certification by the Executive Agency “Bulgarian Accreditation Services”. This verifies that the operation of the laboratory meets the requirements of БДС EN ISO 17025:2006 standard and can meet the highest international standards. 

The LTC performs monitoring related to ascertaining the quality of potable water in the water network on the grounds of a program approved by the Regional Health Inspectorate – Sofia Region. The potable water sector performs tests by three main groups of indicators – microbiological, physicochemical and hydrobiological.

According to a preset schedule sample-taking and analyses of samples from the water sources, potable water treatment plants, servicing reservoirs, as well as from 83 sampling points along the distribution network are performed. Each month a huge number of samples arrive in the LTC’s Potable Water sector, for which over 10,000 analyses for over 50 indicators are performed. Each year the laboratory testing complex of Sofiyska Voda performs over 140,000 analyses on 8000 samples.

LTC also tests samples taken following signals relating to deteriorated quality of the water along the water supply network. LTC specialists take samples and conduct tests within seven days of the sample-taking.

Sofiyska Voda ensures a continuous online monitoring and constantly tracks Key Performance Indicators of the water at the inlet and the outlet of the potable water treatment plants Bistritsa and Pancharevo. Real-time monitoring of the most important data on the quality of the water (such as level of residual chlorine) is also performed in the facilities of the water supply system. The processes of wastewater and sludge treatment are also subject to constant monitoring.

The accredited laboratory testing complex of Sofiyska Voda also provides dozens of certified laboratory services outside those, which are mandatory under the statutes.

Usually the “white” color of the water is the result of its aeration – i.e. its saturation with microscopic air bubbles which “fly away” in a few seconds. It is a myth that “white” water contains a lot of chlorine. If you leave the water in a glass for a few minutes, the water will become transparent. If sludge appears, contact the WSS operator. 

The raw water the WSS operator uses is a natural environment for microorganisms. Although part of them are harmless to the human organism, others may cause diseases. That forces a mandatory chemical processing of the water in the treatment plant of the WSS operator. Disinfection of the water is performed with chlorine gas, that is why sometimes the water from the tap may smell of chlorine. In such case, it would be a good idea to put the water in the refrigerator in a covered glass jar. That will naturally reduce the smell or the taste of chlorine. Consume the water within 24 hours – that is the recommended period, in which there is no danger of the appearance of microorganisms. 

- The materials used in the WSS system – The internal water supply installation, even the small components such as O-rings or liners, may worsen the taste and smell of the potable water at home or at the condominium. Usually many different elements are connected to the household network, such as heaters, pipes, return and other types of valves, taps, shower heads, potable water tanks and hydrophores etc. They have been made of different materials, which enter into contact with the water, as each one of them may potentially alter the water quality. The smell or taste of rubber could be caused by different rubber liners, coatings, flexible pipes etc. 

- The age of the network – The deterioration of the water quality at the end consumers results frequently from the depreciated plumbing and drainage systems in a building. Old riser pipes or water pipes may change the taste, odor, color, and may even cause turbidity of the drinking water. It is important to know that the replacement of the riser pipes in the property of only one household in the condominium will not guarantee the water quality improvement in the building because the water passes through the entire system.

- Back-siphonage – Back-siphonage may occur with household appliances connected to the internal plumbing system (washing machine, dishwasher, electric water heater, etc.) – dirty water flowing backwards into the plumbing system. These appliances may cause flowing back of the dirty water from the appliance into the clean drinking water, and may also include materials that are not intended for drinking water use (flexible hoses, rubber vessels, etc.). Make sure that all household appliances are disconnected from the drinking water system with a check valve. In case of wrong installation or lack of a check valve, the toilet cistern may also cause backflow of water into the building plumbing system and be a potential source of contamination especially if disinfecting or scented toilet cleaning tablets are used.

- Repair works in the building - When repairs are executed of the public water supply network or a neighboring building the color of the water at home might turn brown or orange. Let the water run for some time and it should clarify.

- In case of prolonged absence - When you have been outside your home for a long period of time, it is recommended that you close your individual water supply installation in order to prevent possible leaks. When you return home after a long absence, let the water flow for a few minutes, so that you drain the stagnant water in the pipes and reduce the possible bad taste. Upon proper operation of the external and the internal WSS network the chance of the occurrence of dangerous microorganisms in the water leading to diseases (such as Legionella. E-coli etc.) is minimum. 

The commercial losses encompass all types of inaccuracies related to measurement of customers’ consumption, as well as mistakes made while data are entered, processed and stored (a reading of water meters and billing), including the unauthorized consumption (thefts or illegal use).

It is any unauthorized water consumption, which includes illegal connections, by-pass (a connection before the water meter), physical damage of the meter, broken seal and water drawn from fire hydrants. 
Sofiyska Voda deems the following activities performed by the users to be illegal water consumption:

What is an ‘illegal connection’ – when the user has been connected to the WSS network without the knowledge and permission of Sofiyska Voda JSC. There is an established procedure under Ordinance No.4 and the Spatial Development Act, which should be observed when a new site is connected to the WSS network.
The following documents are required:
1. Initial data;
2. Preliminary contract (as per art.143. para.1, item 3 of the Spatial Development Act);
3. Approved design for the water and sewer service connection;
4. Contract for connection (as per art.84 of the Spatial Development Act)
5. Opinion on the constructed WSS connection.

In case the mentioned documents are not available, the new WSS connections are deemed to be constructed illegally.

1. Another connection to the property or a connection before the water meter (by-pass) – the user is a customer of the company. There is usually another connection or a connection before the revenue meter for a tap in the yard, irrigation system or another construction (backyard kitchen). Thus the water is not registered by the revenue meter and not paid accordingly. 

2. Illegal reconnection to the network done by the customer – the connection of the customer has been cut for unpaid bills but he has been again connected to the WSS network without the knowledge and permission of Sofiyska Voda JSC.

3. Damaged water meter – the customer has damaged deliberately the water meter in order to affect its accuracy. For example:

- Broken glass cover of the water meter
- Use of wood clamp, magnets, etc. 
- Wrong installation (in reverse) of the water meter – the customer has installed the water meter in reverse and it reads backwards to the intended reading.

4. Broken plastic seal – the customer has broken the plastic seal in order to dismantle or manipulate the water meter.

In case the customer has doubts about the accuracy of the water meter or notices any damage on it, including a broken seal, he/she has to immediately inform Sofiyska Voda JSC.
Activities on the water meter node and/or the water service connection, related to dismantling and repair, performed by persons unauthorized by Sofiyska Voda, are deemed to be in breach of and penalized by virtue of Ordinance No.4 and the General Terms and Conditions. 


1. Illegal connection
In case an illegal connection to the WSS system is found, the respective connection will be cut, and the consumed, drained and treated volumes of water will be determined by the flow rate of the water pipe just before the water meter, having in mind consumption for 6 hours per day and flow of water at the speed of 1 m/s for a period of one year unless it is proved that the period has been less than one year. In these cases the water supply and sewerage services are cut off for the entire property without prior notification.

2. Manipulated water meter and broken seal
In case the intactness of the seals is damaged, except in the cases where it has not been caused by actions of the user, and any manipulations that have caused a damage to the water meter or inaccuracy of the readings, the consumed water volume will be determined by the flow rate of the water pipe just before the water meter, having in mind consumption for 6 hours per day and flow of water at the speed of 1 m/s for the period prior to the previous actual reading but no longer than 6 months. 

In case of theft or damage of the water meter when it is the fault of the customer (frozen water meter, broken glass or other mechanical damages), its repair and replacement will be done by the operator at the expense of the customer.

Table with the flow rates under the General Terms and Conditions for the provision of WSS services to the customers by WSS operator Sofiyska Voda JSC

V speed m/s

D (diameter) mm






(13 mm) 1/2"






(19 mm) 3/4"






(25 mm) 1"






(32 mm) 1 1/4"






(38 mm) 1 1/2"






(50 mm) 2"






(63 mm) 2 1/2"






(80 mm)






(100 mm)






(125 mm)






(150 mm)





Sofiyska Voda is a personal data controller as per art. 3, para. 1 of the Personal Data Protection Act, registered in the Register of personal data controllers and registers kept by them with identification number № 8046.
The whole staff of Sofiyska Voda is obliged to comply with a personal data privacy policy and respectively any third party signs an agreement regarding this. Any third party which has access to our customers’ personal data has signed a contract to ensure confidentiality of the information.
Sofiyska Voda uses the data to improve the level of service and customer awareness.
The company is not entitled to provide access to your personal information to any third party which intends to use it for direct marketing purposes.

With difference between the indication of the general water meter and the sum of the consumption in the detached properties (the consumption of the individual water meters and the indicated base of the inhabitants’ number) for the three months, according to clause 39, paragraph 4 of Ordinance №4, the same is allocated among the households according to the individual consumption of each property. “Sofiyska voda” AD reads monthly the indications of the general (incoming) water meter in the building, which is installed on the building’s water house connection and which shows the whole quantity used water by the customers. The individual water meters are read on each three months. The quantity “common usage” is included in your water bill only once in each three months, i.e. after the actual meter reading of all water meters. In this way during the first two months you receive invoices without “common usage” included, and on the third month it will be allocated among the households and respectively – included in your invoice. The quantity “common usage” may be caused by different reasons, as an example: the inner W&S installation of the building is not in a good technical shape and there are detected slight leakages; there are no legalized individual water meters installed in each property and the consumption there is defined according to the inhabitants’ number (which doesn’t affect to the actual consumption); for some of the water meters have past 10 years from the previous metrological check-up, which can affect the precision of the measuring.

The water bill for domestic customers is formed in two ways: by the indications of the water meters or on the base of inhabitants’ number. When they have water meters installed on each water deviation (standpipe) in the house and they are registered in the data base of “Sofiyska voda” AD, after they are legalized, the bill is formed according to what meters indicate. Our meter reader reports the indications of the water meters each three months. In the two medium months monthly is billed an average water consumption based on the average consumption of the household for previous period. After the quarterly actual meter reading, the bill is leveled according to the real water consumption in the property. The general (incoming) water meters of the buildings are read each month. As an exception it is allowed for users, which have no water meters installed on each standpipe or there are such, which are not legalized with plastic seal and which are not registered in the data base of the company, the bill for water is formed on the base of the inhabitants’ number. According clause 39, paragraph 5, and point 1 of Ordinance №4 the monthly base for one inhabitant is 6 cubic meters, when the house has a healing installation, and 5 cubic meters, when the house has no healing installation. In block of flats where is registered some difference between the indicated quantity water of the general water meter and the sum of the consumption in the detached properties (the consumption of the individual water meters and the indicated base of the inhabitants’ number) for the balance-sheet values’ period between two actual readings, to the individual expense is added the respective quantity to the “common usage”.

“Sofiyska voda” AD gives an opportunity to pay the debts for water by partial payments and not necessarily covering the whole month bill. In this way you can define the size of the month payments by yourself, as we inform you in your invoice that for the rest of the debt will be included month interest. If you have bigger unpaid debts, the titular of the account or an authorized by him person can conclude an agreement for payment by installments. The original installment is 30% of the whole debt for physical person and 50% for juridical person. The rest of the debt is spaced out to the contractual date without deficit of the month interest. Except for the defined month installments covering the debt of the concluded agreement, it must be also paid off the current bills. For information about all payment methods please visit our Service Centres  or call (+359) 800 121 21.