My tap water is turbid or white. Is there a problem or is it just air?

Water with bubbles has trapped air in it and appears turbid. Another cause of water discolouration is the build-up of limescale deposits. Healthy drinking water contains dissolved natural salts that add taste and nutritional value to the water. Dissolved salts existing in natural waters undergo sedimentation and pass through to tap water, giving it a white, milky colour. Such problems in the appearance of water can result from maintenance work carried out on the distribution network and do not in any way pose a risk to consumer health.

You can determine whether the water discolouration is due to trapped air or limescale deposits by performing the following simple test.

Fill a glass with tap water and let it settle. If the water contains trapped air, in approximately 10 minutes it will clear up and you will notice the air bubbles moving upwards until the water becomes completely transparent. If the water contains limescale deposits, it will need approximately one hour to become transparent and the limescale deposits will sink to the bottom of the glass. In other words, the water will start to become transparent from the top to the bottom.

In each of the above two cases, there should be no water discolouration after three hours, when the flow of the water through the pipes is restored to normal levels. If the problem persists, please contact us for more information.

My water seems to have some colour, what should I do?

In order to determine whether the water discolouration is due to the network or your house’s piping, compare your tap water to that of a neighbouring house. If the problem is found only in your tap, then it is likely that there is a problem with your house’s piping. However, if the problem arises from the network, then the water from the neighbouring house’s tap will have the same discolouration. In such case, contact us for more information.

How "Hard" is the water in our city?

Hardness represents the concentration of dissolved calcium and magnesium salts, and depends on the rocks the water has passed through. The term ‘hardness’ is used to define water that does not foam well when used for washing with soap, and forms limescale on the inner surfaces of domestic appliances. High hardness values are not harmful to one’s health. On the contrary, a correlation has been found between high hardness levels and a reduction in cardiovascular diseases.

There are no specifications regarding the hardness value of drinking water in the health regulation.

The hardness of water is measured in mg CaCO3/l, in German and in French degrees. The following factors can be used to convert from one unit of measurement to another:

1 French degree = 0.56 German degrees

1 German degree = 1.79 French degrees

1 French degree = 10 mg CaCO3/l

1 German degree = 17.9 mg CaCO3/l


Classification of water depending on the level of hardness

VERY SOFT0 – 7,160 – 40 – 71,6
SOFT7,16 – 14,324 – 871,6 – 143,2
SEMI-HARD14,32 – 21,488 – 12143,2 – 214,8
SEMI-HARD21,48 – 32,2212 – 18214,8 – 322,2
HARD32,22 – 53,7018 – 30322,2 – 537,0
VERY HARD> 53,70> 30> 537,0


Consult the below table for information on the hardness value of the water in your area. Based on the below values, you can adjust your washing machine to the hardness of the water in your area. Washing machine manufacturers often require this adjustment in order to ensure the proper operation of the appliance.


Hardness values by area

AreaHardness Values (German degrees)
EVOSMOS12 – 17
METEORA12 – 13
NEAPOLI12 – 17
SYKIES13 – 15
PEFKA14 – 15
ΚΕΝΤΡΟ16 – 17
NEA KRINI13 – 14
ARETSOU14 – 15
NTEPO14 – 16
DELFON14 – 16
KIFISIA12 – 13


Is chlorine necessary in our network? Do we have a lot of it in our water supply network?

Chlorine is used as a disinfectant during the distribution and treatment of water. By disinfection we mean the destruction of pathogenic microorganisms contained in water.

Chlorination takes place on a 24-hour basis with modern technology at the central water treatment plants and at the points where water is made available to consumers from the central pumping stations.
The main form of chlorine used is anhydrous liquid chlorine (chlorine gas).

According to the legislation, water chlorination is carried out in such a way that a minimal amount of residual chlorine remains in order to deal with infections when distributing water to consumers. This small amount of residual chlorine is completely harmless to human health, since it is neutralised by saliva and gastric acid.

The disinfection of the distribution network of the Thessaloniki Urban Area is checked daily by the Drinking Water Laboratory Testing Department by measuring the free residual chlorine in the distribution network. The presence of residual chlorine is constant and is detected throughout the distribution network all the way to its endmost points, in accordance with the provisions of the health regulation.

The legislation also makes provision for the monitoring and measurement of chlorination by-products, which is carried out at the Water Treatment Plant Laboratory for the entire EYATH S.A. network, as frequently as is required by current legislation.
These are known as trihalomethanes and consist of the following four compounds: chloroform, bromoform, dibromochloromethane and bromodichloromethane. They are produced due to the reaction of the free chlorine in drinking water with the organic carbon that may be contained in it.

In accordance with current legislation, namely Joint Ministerial Decision No. Γ1(δ)/ΓΠ οικ. 67322/Government Gazette B 3282/19.09.2017, in compliance with Directive 98/83/EC on the quality of water intended for human consumption, as amended, trihalomethanes are measured 16 times a year and the total maximum parametric value should not be higher than 100 μg/l.

Based on the measurements carried out by the Water Treatment Plant laboratory, the concentrations of trihalomethanes in drinking water are far lower than the applicable statutory limit of 100 μg/l.

What can I do if the water smells like chlorine?

Consumers often complain that their tap water smells like chlorine.

In order to reduce the smell of chlorine, you can fill a glass bottle with water and leave it in the refrigerator overnight. The smell will have disappeared the next morning.
Caution! Refrigerated water in any container must be consumed within 24 hours.

Can I use a water tank or pressure booster pump?

If the water reaches your household through a water tank or pressure booster pump, there is a risk that the water may become infected due to stagnation and higher temperatures, and this water usually has fewer organoleptic properties compared to running water reaching your household directly from the water supply network. It should be noted that under the EYATH S.A. Water Intake Regulation, water tanks are prohibited for reasons of health protection of the water supply network (possible suction into the water supply system). For this reason, any connection to the water supply network (water meter column: meters) must have a check valve.

Home owners must ensure that any existing pressure booster pumps are regularly maintained and cleaned, as are any water tanks until their permanent removal, in order to avoid the degradation of the quality of the water they consume.

Should I install a filter at home?

We do not want anything to come between us!

  • The water meets all applicable national and European requirements in all respects (including heavy metals, pesticides, pathogenic organisms, etc.).
  • Any further treatment with the use of filters or any other means is therefore not necessary. It is redundant and adds unnecessary costs to consumers.
  • EYATH S.A. has processed, cleaned and disinfected the water, were and however necessary. In other words, EYATH S.A. has already done for us what any filter would.
  • When the Drinking Water Laboratory Testing Department gets to the consumer’s tap in order to collect a sample, it either requires that any filter or treatment unit installed by the consumer be bypassed or that samples be taken from taps that are not affected by it.
  • Sometimes filters, especially those that are not properly maintained but also those that are, can harm instead of improve the quality of the water both from a chemical and microbiological aspect.
  • “Desalination” filters that de-ionise water can even prove to be harmful to one’s health. A certain number of minerals is necessary for the proper function of one’s body. De-ionised water is non-drinkable!
  • Filters that consume residual chlorine long before the water reaches your glass can prove to be even more harmful to one’s health considering that, by “neutralising” the residual disinfectant effect of chlorine, it may render the water vulnerable to microbiological infection.

The Ministry of Health has pointed out that if a consumer chooses to add materials such as water filter appliances after the water outlet and on the tap, which is also the point of final control of water quality, in accordance with current legislation, then it shall no longer fall within the scope of competence of the bodies responsible for the quality of water following the interference of the filter.

Can I drink from the hot water line? The water is very cold in the winter.

  • Never drink water from the hot water or mixer tap. Drink only from the cold water tap!
  • The hot water line, even when mixed with cold water, does not provide drinking water. It may be chemically or microbiologically degraded!
  • If you need to use the hot water, once you are finished using the hot water turn it back to the cold water line and wait for it to regain its regular cool temperature before drinking.
  • You can check the water’s temperature with the tip of your finger whenever you turn on the tap to drink water.
  • When a household functions under normal conditions, it becomes immediately clear when standing water has been cleared from the internal piping and when the water running from one’s tap is the fresh, cool water from the network, which we can consume without hesitation.
  • The improvement of taste and odour following this simple test is truly impressive!

One does not need any filters, cotton wool and plastic bottles. EYATH S.A. Provides top quality water!

Does asbestos in the networks affect the quality of drinking water?

Asbestos is a fibrous silicate mineral that contains iron, magnesium, calcium and sodium. None of the elements it contains are harmful to one’s health when they are found in water in concentrations permitted by the regulations. However, its use in the construction of water pipes and the possible suspension of asbestos fibres in drinking water have sparked the interest of the public and have concerned various organisations. This interest and relative concern have been caused by the fact that inhaled asbestos fibres are carcinogenic.

The World Health Organisation claims that although the carcinogenicity of inhaled asbestos is well established, there is no conclusive evidence that asbestos ingested with drinking water has negative effects. This is the latest response to recent concerns arising from the use of asbestos cement in water pipes.

Circular No. ΔΥΓ2/19028 on “asbestos pipes in the water supply network” does not include asbestos fibres in the parameters that must be controlled in drinking water, and it further states: “As regards the health effects of swallowing asbestos fibres with drinking water, the conclusions of studies in the international literature have not established a direct correlation between the potential presence of asbestos fibres and health effects from swallowing such fibres”.

To date, asbestos fibres have not been detected in the drinking water of the Thessaloniki Urban Area. Analyses for the detection of asbestos fibres in drinking water are carried out on behalf of EYATH S.A. at specialised third-party laboratories. It should be noted that for this parameter there is no limit to.


Who does the Special Sewerage Regulation (SSR) concern and which areas does it cover?

SSR-Article 1:

  1.  “… concerns the terms and conditions imposed on professional, industrial, craft activities, educational institutions (public entities), laboratories, etc., and any kind of activity and organisation that may produce liquid waste, other than residential, for the disposal of liquid waste in the sewerage network of the Thessaloniki Water Supply and Sewerage Co. S.A. (EYATH S.A.).”, and

b) “…covers the entire area in the competence of EYATH S.A., as defined in article 26 of Law 2937/2001 (Government Gazette 169/A/26.7.2001) and subsequent amendments”.

What is domestic wastewater?

SSR-Article 2-Basic concepts: Domestic Wastewater – Wastewater from residential and service areas, primarily derived from functions of the human body and commercial activities.

What is liquid industrial waste?

SSR-Article 2-Basic concepts: Liquid Industrial Waste – liquid waste produced from any occupational activity, which is not domestic wastewater or rainwater.

Which business categories are required to have a sampling well?

Any activity apart from residential homes from which liquid industrial waste is produced.

Which businesses should have separate internal wastewater and liquid wastewater networks?

Any activity apart from residential homes from which liquid industrial waste is produced and installed in new facilities (not already existing).

What is the licensing procedure followed for businesses in category B?

Described in the SSR-Article 6.3.1-6.3.2-6.3.3

What analyses should I conduct on the outflow of my business’ treated liquid wastewater?

An indicative list of the controlled parameters is provided in Annex VI.

Is the sample taken instantaneous or weighted?

Sampling concerns random instantaneous samples (SSR-6.3.3) unless a sampler exists, in which case a weighted sample can also be taken.

From which point of my business’ Waste Treatment Facility can samples be taken to control outflow quality?

The samples are taken from the point described in the wastewater treatment and disposal design approved by EYATH S.A. in the presence of the company manager.

For how long are exceedances of specific parameters “allowed”?

They are allowed for one year only. Parameters for which exceedances are allowed are: TSS, COD and BOD5. During this time, and only for the specific above parameters exceeded, the business will be charged with an Additional Treatment Cost Fee (ATCF) (Annex IV).

The ATCF is in addition to the sewerage charges.

Where exceedances take place for over one year, the wastewater disposal permit is revoked, as stated in article 8.

What happens if there is no possibility of separating the domestic wastewater and industrial liquid wastewater networks?

The limits of the Special Regulation apply. Under no circumstances may the acceptable limits for the disposal of liquid wastewater in the EYATH network be achieved (Table I of SSR Annex I) by dilution (Article 5.1-SSR).

Do I need to install a flow meter at the exit of my Waste Treatment Facility?

All businesses producing liquid waste with a flow of > 2m3/d must install a flow meter.

Where will I find specifications for the flow meter?

Before the flow meter is procured, its specifications must be approved by EYATH S.A. as reported in the SSR-Par. 6.5.

What applies to health units?

Their wastewater should be managed in accordance with JMD 146163 (Government Gazette 1537/Β/8.5.2012) “Measures and Conditions for the Management of Health Unit Waste” and with Circular with Internet Publication No.: 9Θ2Ο465ΦΥΟ-Τ2Ω on the management of health unit wastewater (Ref. No. Δ1ε/.Π.33942/17 (21-02-18).

What should I do if my Waste Treatment Facility presents a fault?

Α) For a flow of wastewater of < 2m3/d


  1. B) For a flow of wastewater of > 2m3/d:


  • have a Management Plan for untreated wastewater, to prevent them from entering the sewerage network.
  • inform EYATH S.A. immediately and in writing, as provided for in the SSR, of the nature and cause of the problem, of the quality and quantity of any untreated wastewater entering its network until the problem is remedied (if this cannot be avoided on the basis of the above Management Plan) as well as of the expected time required to restore the operation of the Waste Treatment Facility.
  • subsequently, depending on the magnitude of the problem, the potential impact on the network and the quality of outflows from your facilities, the competent bodies should be informed.



  • Faults due to the absence of backup critical E/M equipment, to the absence of a generator and, more generally, to reasons not related to force majeure, are not considered justified.
  • In any case, EYATH S.A. reserves the right to claim any extra costs arising from the receipt at its facilities of waste whose quality is out of contract.

What happens when it is not possible to connect my operation to the EYATH network ?

If there is a septic tank and the collected wastewater is transported to the Thessaloniki Wastewater Treatment Facility or the Aeneia Wastewater Treatment Facility, the procedure of paragraphs 6.3.2. & 6.3.3. applies with the aim of issuing a wastewater transport license.

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