Waters Protection Ordinance (WPO) (WPO)
English is not an official language of the Swiss Confederation. This translation is provided for information purposes only and has no legal force.
Section 1 Differentiation between Polluted and Non
Art. 3
1 The authorities shall assess whether wastewater entering a body of water by way of discharge or infiltration is considered to be polluted or non-polluted, taking account of: a. the type, the amount, the characteristics and the temporal occurrence of potential water pollutants substances in the wastewater; b. the condition of the receiving waters. 2 During infiltration of wastewater, they shall also take account of whether: a. wastewater can be polluted because of existing soil pollution or the unsaturated subsoil; b. wastewater is sufficiently purified in the soil or in the unsaturated subsoil; c. guide values under the Ordinance of 1 July 1998 on the Pollution of Soil (SoilPO) can be maintained in the long term, excepting infiltration into a plant intended for this purpose, or onto roads next to embankments or grass verges. 3 Precipitation water running off built-up or sealed surfaces is as a rule considered to be non-polluted wastewater if it: a. originates from roof surfaces; b. o
Para. 2 let. b — Amended by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955). Para. 2 let. c — SR 814.12 Para. 3 let. b — Amended by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955). Para. 3 let. c — Amended by No I of the O of 4 May 2011, in force since 1 June 2011 (AS 2011 1955).
Section 2 Drainage Planning
Art. 4 Regional drainage planning
1 The cantons shall ensure that a regional drainage plan (RDP) is drawn up to guarantee appropriate waters protection in a limited, hydrologically-related area in which waters protection measures of the communes must be coordinated. 2 The RDP determines in particular: a. the locations of wastewater treatment plants and areas which are to be joined to them; b. which and to what extent surface waters are suitable for the discharge of wastewater, particularly that arising from precipitation; c. the wastewater treatment plants for which requirements in respect of discharge of wastewater must be stricter or supplemented. 3 In drawing up the RDP, the authorities shall take account of spatial requirements of waters, flood protection and measures for waters protection other than wastewater treatment. 4 The RDP is mandatory for planning and establishing of waters protection measures in communes. 5 It shall be accessible to the public.
Art. 5 Communal drainage planning
1 The cantons shall ensure that general drainage plans (GDP) are drawn up which guarantee adequate waters protection in communes and effective drainage of housing areas. 2 The GDP shall specify as a minimum: a. wastewater treatment areas that must be served by public sewers; b. areas in which precipitation water running off built-up or sealed surfaces must be disposed of separately from other wastewater; c. areas in which non-polluted wastewater must be allowed to infiltrate; d. areas in which non-polluted wastewater must be discharged into surfacewaters; e. measures by which non-polluted wastewater with permanent flow must be kept away from wastewater treatment plants; f. the locations where wastewater treatment plantsmust be set up, and withwhich treatment system and with what capacity; g. areas in which systems other than wastewater treatment plants must be used, and how, in these areas, wastewater is to be disposed of. 3 The GDP shall be adjusted if necessary: a. to take account of
Section 3 Discharge of Polluted Wastewater
Art. 6 Discharge into waters
1 The authorities shall authorise the discharge of polluted wastewater into surfacewaters, drainage areas, underground rivers and streams if the requirements on discharge into waters according to Annex 3 are complied with. 2 They shall set additional or stricter requirements, if: a. the waters concerned by the discharge of wastewater do not fulfil water quality requirements according to Annex 2 or if this is necessary to comply with international agreements or decisions; and b. on the basis of investigation (Art. 47) it is certain that deficient water quality is largely due to discharge of wastewater, and procedures necessary to comply are not disproportionate for the wastewater treatment plant. 3 They may set additional or stricter requirements if the water quality according to Annex 2 is not sufficient for a specific use of the body of water concerned. 4 They may apply less stringent requirements if: a. by reducing the amounts of wastewater discharged, fewer potential water pollutant
Art. 7 Discharge into public sewers
1 The authorities shall authorise discharge of wastewater from industry according to Annex 3.2 or of other wastewater according to Annex 3.3 into public sewers if the requirements of the relevant Annex are complied with. 2 They shall set additional or stricter requirementsif by discharge of wastewater: a. operation of public sewers may be restricted or disrupted; b. in the case of wastewater from the central wastewater treatment plant, the requirements on discharge into a body of water are not met or may only be met by disproportionate measures, or could restrict or disrupt the operation of the plant in another way; or c. ... d. the operation of the plant in which sludge is incinerated may restricted or disrupted. 3 They may apply less stringent requirements if: a. by reducing the amounts of wastewater discharged, fewer potential water pollutants are discharged even though the concentrations allowed are higher; b. the environment as a whole will be less impaired by the discharge of non
Para. 2 let. c — Repealed by No I of the O of 4 Nov. 2015, with effect from 1 Jan. 2016 (AS 2015 4791).
Art. 8 Infiltration
1 The infiltration of polluted wastewater is prohibited. 2 The authorities may authorise the infiltration of communal wastewater or of other polluted wastewater of comparable composition, if: a. the wastewater has been treated and meets the requirements for discharge into waters; b. in the case of the groundwater concerned, water quality requirements according to Annex 2 are met after infiltration of the wastewater; c. infiltration ensues at an installation intended for the purpose, the directives of the SoilPO are not exceeded even in the long term, or in the absence of directives soil fertility is also guaranteed in the long term; and d. requirements valid for wastewater treatment plants which discharge wastewater into a body of water are met (Arts. 13–17).
Para. 2 let. c — SR 814.12
Art. 9 Wastewater of specific origin
1 Polluted wastewater occurring outside public sewers for which neither discharge into waters, nor infiltration, nor use combined with farm manure (Art. 12 para. 4 WPA) is permitted must be collected in a cesspit which is regularly emptied with its contents being transferred to a central wastewater treatment plant or facility for special treatment. 2 Wastewater from processing farm manure, hydroponics and other horticultural methods must be used in an environmentally compatible manner and reused agriculturally or horticulturally according to the state of the art. 3 Wastewater from mobile sanitation facilities must be collected and may be discharged into public sewers only by using equipment intended for this purpose. Excluded from this are sanitation facilities in: a. railway carriages with their own wastewater treatment facilities; b. railway carriages for long-distance traffic which were commissioned before 1 January 1 1997; c. railway carriages for regional or urban traffic which we
Art. 10 Prohibition of waste disposal with wastewater
It is prohibited: a. to dispose of solid and liquid wastes with wastewater unless this is expedient for treatment of wastewater; b. to discharge substances in a way which is contrary to instructions on the manufacturer’s label or in the directions for use.
Section 4 Construction and Operation of Wastewater
Art. 11 Separation of wastewater in buildings
During construction or substantial building alterations, the persons responsible for the buildings must ensure that precipitation water and permanent flows of non-polluted wastewater are channelled off separately from polluted wastewater prior to reaching the outside of the building.
Art. 12 Connection to sewers
1 The discharge of polluted wastewater into public sewers outside building zones (Art. 11 para. 2 let. c WPA) is: a. expedient if the connection may be constructed properly and with standard building expenditure; b. reasonable if the costs of the connection do not substantially exceed those for comparable connections within the building zone. 2 The authorities may only authorise new discharges of permanent flows of non-polluted wastewater into a central wastewater treatment plant (Art. 12 para. 3 WPA) if local conditions do not permit infiltration or discharge into a body of water 3 In order for a farm to qualify for exemption from the bond to be connected to the public sewers (Art 12 para. 4 WPA), its cattle and pig stock must comprise at least eight livestock units.
Art. 13 Expert operation
1 Persons responsible for wastewater treatment plants must: a. maintain the facilities in working order; b. identify cases of divergence from normal operation, clarify the causes and immediately rectify these; c. during operation take all reasonable measures to contribute to reducing the amount of substances discharged. 2 Persons responsible for enterprises discharging industrial wastewater into public sewers as well as persons responsible for wastewater treatment plants discharging wastewater into the public sewers or into a body of water must ensure that: a. those responsible for the operation are named; b. operating staff possess the necessary expert knowledge; and c. that amounts and concentrations of substances discharged are determined if the authorisation contains numerical requirements. 3 Under paragraph 2, the authorities may require that owners: a. determine the amounts and concentrations of substances discharged which would influence the quality of the polluted water and of
Art. 14 Operational reports
1 Persons responsible for enterprises that discharge industrial wastewater into public sewers and persons responsible for wastewater treatment plants who discharge wastewater into public sewers or into a body of water must report to and as instructed by the authorities: a. the amount of wastewater discharged; b. the amounts and concentrations of substances discharged which they must determine according to Article 13. 2 Persons responsible for central wastewater treatment plants must also report: a. important operating data such as degree of effectiveness, quantity and characteristics of sludge, type of sludge disposal, energy consumptionand operating costs; b. conditions in the catchment area of the plant, such as connectionrate and the percentage of non-polluted wastewater with permanent flow.
Art. 15 Supervision by the authorities
1 The authorities shall examine periodically whether: a. enterprises which discharge industrial wastewater into public sewers, and wastewater treatment plants which discharge wastewater into public sewers or into a body of water are complying with the requirements set out in the authorisation; b. these requirements continue to guarantee adequate waters protection. 2 For this purpose, they shall take account of the results of the assessments made by the person responsible. 3 They shall adjust the authorisations if necessary and order the required measures. In doing so, they shall take account of the urgency of the required measures, as well as the obligations resulting from international agreements or decisions.
Art. 16 Measures with reference to exceptional events
1 The persons responsible for wastewater treatment plants that discharge wastewater into a body of water and persons responsible for enterprises who discharge industrial wastewater into a wastewater treatment plant must take appropriate and economically acceptable measures to reduce the risk of pollution of a body of water arising from exceptional events. 2 If in spite of these measures the risk is unacceptable, the authorities shall order the necessary additional measures. 3 Regulations in the Major Accidents Ordinance of 27 February 1991 and the Ordinance of 20 November 1991 on the Guarantee of Drinking Water Supplies in Emergencies that go further are reserved.
Para. 3 — SR 814.012 Para. 3 — [AS 1991 2517, 2017 3179 No I 2. AS 2020 3671 Art. 15]. See now: the O of 19 Aug. 2020 (SR 531.32)
Art. 17 Reporting on exceptional events
1 Persons responsible for wastewater treatment plants that discharge wastewater into a body of water must ensure that any event which is exceptional is reported immediately to the authorities, if such an event or events could lead to a situation in which it is no longer possible to guarantee compliance with the regulations on the discharge of wastewater into a body of water or the intended use or disposal of sludge. 2 Persons responsible for enterprises that discharge industrial wastewater must ensure that exceptional events are immediately reported to the owner of the wastewater treatment plant if these could lead to a situation in which the normal, orderly operation of the water or wastewater treatment plant is restricted or disrupted. 3 The authorities shall ensure that the communities and individuals affected by an exceptional event are informed about possible harmful effects on waters in due time. If substantial effects may be expected beyond cantonal or national boundaries, they
Para. 4 — Repealed by No I of the O of 4 Nov. 2015, with effect from 1 Jan. 2016 (AS 2015 4791).
