Reviews of Current Knowledge - ROCKs

rock image

We publish ROCKs to meet the need for unbiased science-based information in a readable format. They focus on water-environment topics of general interest. Our policy is continually to revise and add to these ROCKs.

A summary, or the complete document (Adobe Acrobat pdf file) may be viewed via the appropriate link.

All ROCKs are available as printed booklets (A5 with the exception of the "Green Infrastructure" and the "Floods" Rocks which are A4), priced at 15.00, less 20% to FWR Members.

Lubeck sludge digester

Sewage Sludge: Operational and Environmental Issues
FR/R0001 Revised June 2016

Sewage sludge is an inevitable consequence of sewage treatment. The quantity produced has increased because of regulations requiring additional standards of treatment and because of increasing population. The various ways in which it can be treated, used or disposed of are discussed as well as the measures that can be taken to ensure no adverse environmental or health effects.

Exmple of eutrophication

Eutrophication of Freshwaters
FR/R0002 Revised August 2006

Eutrophication is the enrichment of natural waters with plant nutrients, largely derived from man’s activities. This disturbs the balance of aquatic life and results in poor water quality. The review explains the causes of eutrophication, the various impacts, and the legislation and initiatives that are being used to control the problem.

Endocrine Disrupters in the Environment
FR/R0003 Revised May 2011

Endocrine disrupters are chemicals that may interfere with hormone systems. Some effects have been seen in certain marine and freshwater organisms, such as fish downstream of sewage treatment works. The review explains what endocrine disruption is and which chemicals have been questioned. There is a discussion of the risks for the environment and for human health compared with other commonly encountered risks.

Legionella sources

Legionella in the Environment
FR/R0004 September 2001

Legionellae are rod-shaped bacteria that can cause Legionnaire’s disease, an acute form of pneumonia. They occur naturally in fresh water, sea water and moist natural environments throughout the world. They prefer warm water, hence most outbreaks of Legionnaire’s disease are associated with cooling towers, evaporative condensers, hot and cold water systems and spa pools. The review explains the growth of the bacteria in water systems, the maintenance factors affecting colonisation of cooling water systems and the efficiency of biocides and other control agents.

Photomicrograph of Cryptosporidium
©Science Photo Library

Cryptosporidium in Water Supplies
FR/R0005 Revised December 2011

Cryptosporidium is a waterborne parasite, which can cause an unpleasant illness called cryptosporidiosis. The symptoms are diarrhoea, mild abdominal pain, nausea, vomiting, mild fever and fatigue. Outbreaks of cryptosporidiosis have been caused by poor hygiene, contact with farm animals, contaminated drinking water and contaminated swimming pools. The review summarises the incidence and principal causes of the disease, and the measures employed by UK water suppliers to prevent infection via the water supply route.

Photomicrograph of Giardia
©Science Photo Library

Giardia in Water Supplies
FR/R0006 Revised October 2012

Like Cryptosporidium, Giardia is a parasite, which can cause an unpleasant illness referred to as giardiasis. The symptoms are acute diarrhoea, abdominal cramps, bloating and excessive flatulence. Outbreaks have been caused by contact with farm animals, contaminated drinking water, contaminated food and contaminated swimming pools and other recreational waters (rivers and lakes). The review summarises the incidence and principal causes of the disease, and the measures employed by water suppliers in the UK to prevent infection via the water supply route.

Copper fittings
©European Copper Institute

Causes of Copper Corrosion in Plumbing Systems
FR/R0007 Revised October 2010

Copper pipework, copper cylinders and copper alloy fittings are widely used for plumbing systems. Internal corrosion by the conveyed water can occur in certain circumstances. The review describes problems that can occur inside the pipework and fittings of water supply systems made of copper and copper alloys (such as brass), how to identify their causes, and how to prevent problems arising.

Water and the Water Environment: a summary of UK legislation and agreements
FR/R0008 August 2003

As a consequence of subsequent and more recent legislative changes this Rock has now been withdrawn. It remains obtainable by special request.


Cyanobacterial Toxins in the Water Environment
FR/R0009 Revised January 2014

Cyanobacteria (blue-green algae) are natural inhabitants of fresh, brackish and marine waters and are of worldwide distribution. They produce a diverse range of small molecules (cyanobacterial toxins: cyanotoxins) which are hazardous to human and animal health. The sources and properties of these toxins are briefly reviewed. Examples of the adverse effects on human health, domestic animals and wildlife are given. Reactive and proactive measures and further needs in this context are presented. The reduction of cyanotoxin problems in natural and controlled waters as a potential benefit of eutrophication control is also discussed.

Household Chemicals

Household Chemicals and the Water Environment
FR/R0010 Revised December 2012

We all use chemicals in the home and in gardens. Some chemicals, such as cleaning agents and detergents, may be discharged directly and legitimately to the drains and hence enter water bodies. Others, such as paints, solvents or surplus pesticides, may be disposed of with little consideration for the environment, and may pose a risk, especially in the long term. This review considers the risks that household chemicals pose to the aquatic environment and the means of controlling these risks.

Sewer construction

Urban Drainage and the Water Environment: a Sustainable Future
FR/R0011 Revised April 2013

This review describes how drainage systems in urban areas developed in order to understand how we have got to where we are today and how systems can be developed to cope with increasing urban populations and changing weather in the future. It covers the issues concerned, including sustainability. If it all goes downthe drain, it has to be pumped and treated. Handled appropriately, surface water could be a less expensive alternative than opening new resources when weather stresses the existing ones.

Swiss Dam

World Water: Resources, Usage and the Role of Man-Made Reservoirs
FR/R0012 Revised March 2010

This review addresses man-made reservoirs that provide water storage and other benefits such as hydroelectric power, flood control and navigation. In many areas the life span of reservoirs is determined by the rate of sedimentation, which gradually reduces storage capacity and eventually destroys the ability to provide water and power. This review considers overall water resources and usage, the world stock of reservoirs, the problem of sedimentation and possible measures to minimise the impact of sedimentation.

©Thames Water Utilities Ltd

Desalination for Water Supply
FR/R0013 Revised June 2015

The scarcity of existing fresh water supplies is becoming a problem in many parts of the world. In some areas a process called "desalination” is used to reduce the salt content of brackish and sea waters to turn them into a drinkable supply. This review explains what makes a water drinkable, the various processes used for desalination and their costs compared with the costs of conventional water supplies.

Green Infrastructure

Surface Water Management and Urban Green Infrastructure - A review of potential benefits and UK and international practices
FR/R0014 May 2011

This ROCK, which has about 200 references, considers the breadth of benefits that urban green infrastructure can play for managing surface water with examples from many countries around the world where the authors have seen GI working and/or discussed it with people who have implemented GI for surface water management.

Flood at Dorchester UK

Floods: alleviation, protection, response and risk management
FR/R0015 July 2011

Flooding is the most widespread of all natural hazards, often arising from adverse meteorological conditions such as:

The main factors which need to be considered regarding flooding include technical, social and governmental aspects. This ROCK aims to provide a concise description of these factors on a worldwide basis but with a more specific European and UK focus.

The role of water in the production of energy
FR/R0016 Revised November 2016

This review is concerned with the role of water as one of the many sources of energy. Other major sources include solid fuels, oil, natural gas, nuclear fusion, biofuels and waste, together with smaller contributions from geothermal, solar, wind and heat. Hydropower, power from water, makes a relatively small contribution towards the overall provision of worldwide energy. By far the largest energy supplies come from solid fuels, oil and natural gas. Hydropower, however, plays a more significant role in the direct provision of electrical energy, 16% of the total world production in 2010.

Water and food security

Water for Food Security
FR/R0017 December 2013

Water and food are inextricably linked as significant quantities of water are required to produce our food. Water is fundamental to agricultural production: crops require water to grow; livestock require water for drinking and hygiene; and farms need water for operations and processing. Inland fisheries and aquaculture cannot exist without freshwater. The water consumed in food production is either sourced directly from precipitation or from soil moisture (green water), or withdrawn from aquifers, streams and lakes (blue water).

The Measurement of Free Surface Flows
FR/R0018 January 2013

Hydrometry embraces the measurement of all the elements in the hydrological cycle including surface water flows, groundwater movement and associated phenomenon such as sediment movement and morphology. This ROCK concentrates on a major element within hydrometry, namely the measurement of free surface flows. It does not cover flows in closed conduits and pipes although some of the methods described can be used for these applications.

Hard Suds

Hard SuDS Infrastructure in the Urban Environment
FR/R0019 June 2014

This ROCK focuses on hard Sustainable Drainage (SuDS) infrastructure, particularly pervious paving systems (PPS), infiltration trenches and rainwater harvesting, discussing their role in the “SuDS triangle”; also covered are the ways in which they can mitigate and adapt to climate change, and address the Urban Heat Island Effect.

Demystifying Natural Water Retention Measures (NWRM)
FR/R0020 September 2014

This review aims to clarify the competing definitions of NWRM and to scope where these measures fit in the context of the Water Framework Directive, other related policies and regulations, and climate change policy. It will outline what the key measures are and will provide some understanding of their evaluation for assessing the technical and economic potential of NWRMs in the UK and elsewhere in the EU.


Community Involvement in UK Catchment Management
FR/R0021 January 2015

This Review of Current Knowledge (ROCK) highlights issues related to monitoring and understanding the complexity of river catchments which are subject to multiple pressures. It details how countries, such as the UK, are beginning to manage catchments on a local level with involvement of local people. Case studies are also presented to emphasise how we are now within exciting times due to the rapid growth in technology and communication facilities, which can and should be utilised in innovative ways (and to our advantage) to support the management of river systems.

Sediments in the Fresh Water Environment
FR/R0022 March 2015

This review of current knowledge (ROCK) is concerned with the movement of sediments in the freshwater environment, an important subject but a very complex one. The ROCK provides an outline of the subject and a description of some of the principles used in the analysis of the many complex processes. However, for details of the analytical methods it is necessary to consult major text books on the subject.

Smart Meters and Domestic Water Usage
FR/R0023 May 2015

This review aims to create a more coherent and integrated understanding of how water metering, through smart meters in particular, can affect domestic demand for water. It also considers the influence of additional factors that serve to shape the effectiveness of metering technologies. It is important to note that the contextual and governance focus of this review, whilst centred on the UK, does draw upon research and information that is more global in scope.

Water Reuse
FR/R0024 September 2016

This Review sets out the facts (and perceptions) and aims to clarify some of the most common questions that people have about ‘water reuse’. It explains the differences between the very small scale and very large scale schemes, the differences between reuse to create non-potable and drinking water, the types of technology used, actual and perceptions of risk, how reuse schemes are regulated and risks managed and finally, an explanation of the energy and other resource requirements of reuse and the implications of these on cost.

Sediments in the Marine Environment
FR/R0025 November 2016

This review is concerned with the movement of sediments in the marine environment. This is an important subject with influence on all nations with a coastline. The review provides an outline of the subject and a description of some of the methods used in the analysis of the many complex processes. However, for details of the analytical methods it is necessary to consult major text books on the subject.