Avoid the pollution of watercourses and land with the correct treatment of runoff water during the design and installation phases.

piazzale di una stazione di servizio durante una forte pioggia
piazzale di parcheggio sotto ad un temporale
First rain or runoff water corresponds to the first 5 mm of rain that falls on car parks or squares, in particular of activities such as refueling areas, car washes, logistics centres, industries, car parks etc...


As the runoff waters flow, they carry with them the polluting elements that have deposited on the asphalt, such as sand, oil, grease, hydrocarbons, or other materials related to the activity that takes place on the square. Water laden with polluting elements cannot be released directly into the ground or into a stream, but must be intercepted and treated according to Legislative Decree 3 April 2006 n. 152. The "Consolidated text on waters" containing "Environmental regulations", has introduced very precise criteria in Italy in the field of responsibilities and methods for treating storm water. Already in the preliminary design phase it is appropriate to provide a water treatment plant that is compliant with the regulations, and guarantees the prevention of soil and water pollution.

REDI is able to offer solutions for the management of waste water and accompanies the designer in choosing the best solution for his job. The legislation is quite complex and can vary according to the region, in a more restrictive sense.


Treatment plants with accumulation and continuously

The choice of which type of implant is most suitable is influenced by several factors:

  • The type of pollutants present in the wastewater to be treated
  • The concentration of pollutants
  • The national and local legislation
  • The final delivery

When is a first rain water treatment plant necessary?

Whenever polluting elements are deposited on the apron, some examples: car parkings, logistics centres, petrol stations, car washes, industrial activities, airports, etc.

illustrazione parcheggio di un supermercato sotto la pioggia
illustrazione area industriale
illustrazione area aeroportuale

1. First rain system with Isea Rain accumulation

Why choose a storage treatment plant?

The system with accumulation, in addition to purification, contributes to the prevention of flooding, in the event of heavy rains or "water bombs" the accumulation tanks serve as temporary storage of rainwater reducing the overload of sewers and bodies of water receptors into which they will pour.

illustrazione di area commerciale

Rain: treatment plant and runoff water release

Rain first rainwater treatment plant, made of polyethylene, carries out the purification of run-off waste from paved surfaces guaranteeing the removal of polluting material and allowing subsequent adduction to the final delivery, in compliance with the indications of the law


Treatment of rainwater from paved surfaces


Uncovered surfaces up to 10,000 m2

Stages of rainwater purification

The polluted water from the yard is stored and treated to be released after a sedimentation time of 24/48 hours, in accordance with regional regulations. The purification is divided into 3 phases:

  • Accumulation
  • Diseoiling
  • Filtration

Second rain

The secondary rainwater is sent via the by-pass pipes directly to the final receiver through the spillway well.

Flooding prevention

Rainwater storage capacity from 3,000 to 50,000 liters of accumulation.

2. First Rain continuous rain system by Isea

Continuous first rain water treatment plant in polyethylene, consisting of a spillway well, equipped with inlet, outlet and by-pass stubs, a sand trap for the sedimentation of sand and aggregates and an oil and hydrocarbon separator with coalescing filter and automatic shutter.

First rain water treatment from paved surfaces.


Flow rates up to 30 l/s
Uncovered surfaces up to 6,000 m2

Stages of rainwater purification

The polluted water enters the spillway which allows the division between first rain and secondary water. The sand trap allows the sedimentation of inert material such as sand, gravel, subsequently the oils and hydrocarbons are captured in the coalescent filter:

  • Sedimentation
  • Separation of polluting elements
  • Final delivery

Second rain

The secondary rainwater is sent via the by-pass pipes directly to the final receiver through the spillway well.

Pollution prevention

Operation of the first rainwater treatment plant in continuous FIRST RAIN

3. Otto-Pe deoilers and desalination plants of Isea

OTTO-PE is the mineral oil separator with coalescence filter and automatic closing device (Class I). Polyethylene oil and hydrocarbon separator, for the treatment of wastewater containing mineral oils.

Treatment of run-off wastewater from outdoor areas, garages, industrial or artisanal surfaces, car parks or car washes.


Flow rates up to 6 l/s

Stages of rainwater purification

The waters coming from the square Otto-Pe oil and hydrocarbon separator in monobloc polyethylene, complete with manhole covers both for inspection and for the collection of oils, floating materials, sands and aggregates. The purification takes place in the following stages:

  • Sedimentation
  • Separation of polluting elements
  • Automatic shutter
  • Hydrocarbon storage chamber

Pollution prevention

OTTO-PE mineral oil and hydrocarbon separator operation


Management of rainwater ISEA

Request information

* Mandatory field

Choose the Aliaxis system that best suits your rainwater management needs

ISEA impianto trattamento acque meteoriche di prima pioggia
Treatments before rain Isea
Treatment plants with accumulation and continuous to avoid the pollution of water courses and land with the correct treatment of run-off water in the design and installation phase.
Sistema di infiltrazione ed accumulo acque Waterlock
Waterlock infiltration and accumulation system
The Waterloc modular system is the effective and innovative solution for the accumulation, drainage and reuse of rainwater. The excess water can be temporarily accumulated and progressively conveyed to the sewers, dispersed in the ground or conveyed to the purification systems for reuse.
sistema modulare per la dispersione acque meteoriche nel terreno
Romold manhole inspection chamber
Plastic manholes are used where longevity, easy handling, absolute water tightness and corrosion resistance are required. Thanks to their long useful life, Romold manholes guarantee longer amortization times for the sewage system. The range includes DN 1000 - 800 - 625 - 500 inspection manholes and kinetic energy dissipating manholes.

Contact our industry expert

Massimiliano Giorgio
Country Category Manager - Below-Ground Drainage & Water Treatment
+39 335 7087 815