Latest product launches


Posted: Monday 7th February 2011

HYDRO International has launched the next generation of its innovative Downstream Defender® advanced hydrodynamic separator in anticipation of tougher UK legislative requirements for treatment of suspended solids and pollutants in surface water runoff.

The new Downstream Defender® has been developed to offer greater design flexibility with optimum efficiency and minimal maintenance, typically achieving greater than 80% removal of grits, silts and oils in a much smaller footprint than conventional gravity or swirl-type devices.

The expectations of the EU Water Framework Directive for improved water quality standards by 2015, the implementation of the Flood and Water Management Act in England and Wales and the Water Environment and Water Services Act (Scotland) are all likely to place demands on highways authorities and developers for increased treatment of runoff from roads, car parks and developments. Says Hydro Stormwater Director Alex Stephenson:

“Much stronger legislative drivers for stormwater treatment are just around the corner in the UK, with this in mind Hydro has developed Downstream Defender® to be ready for significantly increased demand. New national standards for Sustainable Drainage Systems are also likely to stipulate treatment requirements and we believe it’s important to set the bar high from the outset.

“This next generation device will offer an unrivalled ability to prevent re-entrainment (or washout), even during peak storm conditions, which could be a critical factor in ensuring adherence to discharge limits in future. More conventional alternatives do not provide protection against solids and pollutants stored in the device from being flushed out during intense storm events.”

In response to customer demand, the new Downstream Defender® also incorporates the option to change outlet pipe direction as needed, meeting Building Regulations requirements without the need to construct a second manhole.

The Hydro Downstream Defender® is expected to be used increasingly to treat runoff from impermeable surfaces where there is a high build up of sediments, floatables and petroleum products such as highways, car parks and industrial areas. It is particularly effective at removing and retaining sediments that carry with them adsorbed chemical pollutants, metals and hydrocarbons.

Downstream Defender® is also ideal for use as part of a treatment train solution for SUDS schemes, for example as an alternative to a sediment forebay, or to provide protection for a detention basin or pond.

Hydro Downstream Defender® comprises a reinforced concrete chamber with internal polypropylene components and no moving parts. The unit is designed to induce a rotational flow pattern with a low headloss, achieving a long, stable flow path to maximise separation of solids, floatables and oils within a small footprint.

Washout is prevented by retaining captured sediments in an isolated storage area at the bottom of the chamber and a built-in trap stores oils and floatables. Sediments are removed periodically by standard vacuum tanker equipment. Maintenance is significantly easier than for diffuse solutions such as gullies or catch pots, enabling longer maintenance intervals and providing a single point of access.

The new Downstream Defender® has four sizing options with diameters of 1.2 m, 1.8 m, 2.55 m and 3.0 m, as opposed to the previous 7 sizes available, offering simplified design parameters for ensuring greater than 80% removal efficiencies of oil and gritspollutants at peak flows predicted volumes. Units can also be designed to achieve meet other defined pollutant removal targets according to site specific conditions and / or performance objectives requiredthe site conditions.

Hydro Downstream Defender® was first developed by Hydro more than 30 years ago and has a proven track record in use both in the UK and the US. It has been extensively tested and its performance verified both by Hydro’s own research and development facilities as well as through independent third party testing and verification programmes, both in the UK and the US.

For more information about the new Hydro Downstream Defender®, or any of Hydro’s storm and wastewater management systems, please call 0800 269371, or visit

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Notes to editor

Hydro International, which has offices in the UK, USA and Ireland, provides cost‑effective solutions for controlling the quantity and improving the quality of water with minimal maintenance. Hydro products have won international awards for outstanding contributions and technical innovation in the water industry. Hydro operates in the water and wastewater sector and the stormwater sector for the construction industry and, offers an enhanced coverage of treatment solutions to the municipal sector.

Press Enquiries to:

Sharon Lindsay, Sharon Lindsay Communications. Email

Tel: 07928 809035; Fax 0161 282 6168.

Issued on behalf of: Hydro International, Stormwater Division, Clevedon Hall Estate, Victoria Road, Clevedon, BS21 7RD. For further technical support, please contact: Catrin Lewis on Tel: 01275 878371, Fax: 01275 874979, e-mail: website:

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