Waste ManagementUseful Information - Sewerage

Sludge disposal

In implementation of JMD 80568-4225-91 “Methods, conditions and restrictions for the use of sludge from domestic and urban waste treatment in agriculture”, upon authorisation by the competent Regional Authority, the calcified sludge stored from previous years is applied to agricultural crops, in the framework of an action implemented since 2011. The committee responsible for authorisations, composed of members of the Environmental, Health and Rural Development Divisions, following a thorough analysis of the soils to be fertilised and sludge sampling, decides on the amount of sludge to be issued per hectare as a fertiliser, thus limiting the amount of chemical fertilisers used. This method of sludge disposal represents a sustainable and eco-friendly action; it is welcomed by farmers in the surrounding areas and has been gaining popularity over time, as it has been adopted in many rural areas (taking part and benefiting from the action each year).


A thermal drying unit of the dehydrated sludge has been in operation since the end of 2011; now, all sludge is led there, producing a hygienised product with grain sizes of 1-4mm and over 92% dryness. This daily quantity (about 20 tons) is received by companies licensed for its management and further utilisation in final product form as a soil enhancer-fertiliser for application to agricultural crops.

Practical adviceto avoid clogging the sewer

Various things that make their way every day into our home’s sinks, washbasins, toilet bowls, bathroom and balcony gutters lead to clogged drains. The sewage system requires particular attention; some simple things we can do every day can delay the clogging of drains; in addition to saving money for your apartment building and household, this will also help improve the operation of the sewerage network, make the operation of wastewater treatment plants (biological treatment) more efficient and consequently reduce the environmental impact.

For these reasons, avoid throwing the following down your drains:

  1. Papers
    Such as toilet paper, tissues and napkins, which are the most frequent cause of clogged drains. Even in the case of things like biodegradable toilet paper, it is best to throw such materials in bins and not in the toilet bowl.
  2. Hair – Soaps
    Such items, which end up down the drain when you are washing your body, can also cause serious problems in the sewage system as balls of hair and soap with water stick to the piping and accumulate there, gradually leading to the clogging of the drains. To avoid or at least limit this problem, use cheap plastic or metal catchers, which you can easily find on the market. These catchers catch the hair, which can then be collected with the aid of paper and discarded in the bin.
  3. Food waste – edible fats and oils and frying oils
    Such materials, which mainly block sink drains, stick to the drain walls and also tend to accumulate, like materials in Category 2. It is recommended that all food waste, except edible fats and oils, be disposed of in waste bins before you wash the dishes. Edible fats, oils and frying oils can be handled as described here.
  4. Personal hygiene products
    Personal hygiene products include nappies, cotton, Q tips, baby wipes, sanitary towels, tampons, dental floss and adhesive dressings. When the above are thrown down the drain, they expand due to the absorption of water, almost directly clogging the drains. It is recommended that personal hygiene products be thrown in the bin and never in the toilet bowl.
  5. Miscellaneous
    The last category includes a large list of materials that cannot be classified in one of the above categories. Examples include cigarette butts, cosmetics, building or renovation materials (e.g. paints, cement, stucco, rubble, etc.), protective gloves, packaging materials, which should be handled in such a way as to avoid clogging the drains and always with a focus on Environmental Protection.


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.

Connect to our networks !