By Dr James Meyer
The Premier Pork Producers (PPP) established a Water Committee, tasked with proactively investigating water quality issues relevant to intensive pig production systems. The following key issues were identified as fundamental requirements needing to be addressed in order to allow PPP to advise its members on how to appropriately manage water for intensive pig production systems.
Key Issue 1:
To increase awareness regarding the effects of water quality on production.
Key Issue 2:
To increase compliance and good practices dealing with water use and discharge.
Whilst these issues deal with separate topics and place emphasis on different considerations regarding water use and water quality, both share commonality in terms of requiring measurements and descriptions of water quality to be made. In order to address these issues the following activities were formulated:
• A series of articles on water quality: Production to compliance
• A series of presentations/workshops on water quality: Production to compliance
• Compilation of a water quality manual: Best management practices for SAPPO/provincial organisations
• Water quality assessments:
i. Tier I: Production
ii. Tier II: Compliance
This article forms the first in a series of four with the aim of introducing the relevant topics for the key issues identified. The objective of the articles is not to provide an exhaustive review of these topics, but to rather introduce the main aspects relevant to the issues by presenting some background and supporting information. It should also be appreciated that within both the informative and descriptive activities a divergent target audience exists, with some members (producers) already having performed aspects of one or both to varying extents.
The sequence of the four articles is as follows:
Article 1: Introduction to water quality for intensive pig production systems
Article 2: Sequenced approach to water quality investigations
Article 3: Water quality guidelines: Cause and effect relationships
Article 4: Emerging research topics
Water quality basics
When reviewing the available literature regarding pig production, water is typically cited as an essential component. Despite this common recognition it is also observed that the effects of water quality are underestimated with much more research required in what is widely regarded as a diverse field, with expertise in toxicology, physiology and nutrition required to appropriately assess the suitability of water for use in intensive animal production systems.
Seddon (1995) noted that whilst water is an essential nutrient it is frequently overlooked, with producers often sending feed samples for analysis when attempting to solve production related problems, but omitting to do so for water as well. The author also noted that a re-formulation of diets may be required in order to correct for poor quality water.
In the Pork 360 Quality Assurance Scheme, the standard referring to water quality specifies:
“Clean potable water must be provided. Biannual testing for microorganisms is advised.”
At first glance this seems to be a reasonable recommendation that should be fairly easy to perform.
In order to evaluate this recommendation it is important to note that potable water is widely regarded as a statement on drinking water with the implication that consumption will incur a low-risk for immediate or long-term harm.
It follows that the literature regarding water quality and pig production and the SAPPO statement both intend for the water quality to be appropriate for the production system to function without any significant adverse effects.
It also follows that several steps are involved that should generally entail sampling, testing (performing analytical procedures), and an assessment.
In all of these steps numerous errors are frequently encountered, from the use of incorrect sampling sites and containers to requesting the wrong analytical procedures. These will be covered in more detail in later articles.
For a start it has to be decided on what to determine analytically. In order to “classify” water as potable or safe it has to be shown to be either be free of potentially hazardous constituents, or to contain concentrations of such constituents at sufficiently low values to not pose any significant risk of an adverse effect occurring.
Different countries each require their own set or list of water quality constituents (WQC) to be tested for. In South Africa, for human drinking water, the Water Services Act 1997 (Act No 108 of 1997) directs bulk water suppliers to the compulsory national standards in the form of SANS 241. The current version is SANS 241-1:2011 which supersedes edition 6.1 of the previous version SANS 241:2006. It presents 46 physical, aesthetic, operational, microbiological and chemical determinands.
In addition, the Department of Water Affairs and Forestry produced South African Water Quality Guidelines in 1993 and then again in 1996 as a series of Volumes, with Volume 1 being for domestic use (human drinking water). There was also a joint publication in the late nineties between the Water Research Commission, the Department of Water Affairs and Forestry and the Department of Health referred to as the quality of domestic water supplies.
A comparison between these South African water quality guidelines for human drinking water reveals them to be very different in two critical aspects. The first relates to the constituents that are cited as being relevant. The second aspect is noted when comparing acceptable concentration limits for the same constituents as they differ significantly, as do the associated risks that are described for the concentration ranges presented.
Comparing the water quality guidelines for human drinking water between the United States Environmental Protection Agency, referred to as maximum contaminant levels and maximum contaminant level goals, the Canadian Water Quality Guidelines, those from the World Health Organisation, and others, it is apparent that the same critical variations exist.
It can therefore be appreciated that for human health the description of “potable water” may be differently interpreted both within South Africa and internationally. It is thus hardly surprising that descriptions for both the constituents considered relevant, and the associated concentrations, also vary in literature dealing with water quality for pigs.
Thus, even if the sampling and analytical steps are correctly performed a critical challenge remains with the assessment step as this requires water quality to be correctly described in order to arrive at the final statement that the observed quality represents a “potable” supply.
The “testing” of water is only of any value if the result is compared to some form of guiding statement or judgment.
Water quality as a function of the Intended use
The South African Water Quality Guidelines (DWAF, 1996) employed what is referred to as the “fitness for use” approach in order to determine or describe water quality.
In this approach water quality is defined in terms of the type of intended use and not simply or generically as poor or good or “potable”. As an example, water that may be fit for humans to drink may not be suitable for use for irrigation purposes, due to long-term soil effects. The one emphasis may thus be on health whilst the other on environmental/production related issues.
Water quality constituents (WQC) refer to properties of water and/or substances suspended or dissolved in the water. A fluoride concentration in water of 2 mg/L simply provides the analytical evidence describing the constituent without offering any statement on whether this represents a desirable concentration or not. It does not offer any guidance on possible effects based on drinking water exposure or the use of such water for irrigation purposes.
For this some narrative is required, linking the concentration in terms of the effects that may occur for the specific use.
Fitness for use thus uses constituents (WQC) and supporting descriptions to provide some guidance on the types of effects that can be expected when using the water for a specific purpose. These types of effects may be considered as affecting a wide range of different aspects of the same use.
As an example, water for domestic use may affect health via drinking water and water that is used for food preparation, but may also be of relevance for bathing and laundry purposes. Drinking water provided for pigs may also affect other aspects of the production system that may have effects not directly linked to pig health. For example, the water may impact on the replacement of water distribution system fittings and fixtures but affecting scaling and corrosion attributes.
These different types of effect categories are referred to as “norms”, and each water use type may require different norms to be considered in order to arrive at a statement on the “fitness for use”.
The combination of the constituent concentration ranges and types of effects are used to develop water quality guidelines which are then used to judge the “fitness for use” for the specific purpose. The South African Water Quality Guidelines (DWAF, 1996) presents separate volumes for the recognised uses, namely:
Volume 1: Domestic water use
Volume 2: Recreational water use
Volume 3: Industrial water use
Volume 4: Agricultural water use: Irrigation
Volume 5: Agricultural water use: Livestock watering
Volume 6: Agricultural water use: Aquaculture
Volume 7: Aquatic ecosystems
It would thus appear to be a simple task to use these guidelines for assessing the fitness for use of water for intensive pig production systems, however, several constraints are applicable.
Again, returning to the use of water for human drinking water as an example, a glance at the international and local water quality guidelines over the last two decades reveals three common trends:
– an increased number of WQCs listed to be able to assess water quality
– a decrease in the concentration limits considered acceptable
– the frequent revision and addition of constituents receiving global research attention
When reviewing water quality guidelines for livestock it is noticeable that few refer to pigs specifically, and many of the guidelines cited are a combination of guidelines used for both ruminants and those derived for human use.
It is not uncommon to see pig producers use the SANS 241 Standard to assess water quality for pig use. The assumption is that if the water is good, or fit for use for humans, then it should also be good for pigs. This is incorrect for several reasons and would incur the same error as assuming it would be good for any other different purpose, such as irrigation or industrial applications (for which far stricter limits may apply).
The SANS 241 Standard is specifically designed with bulk water suppliers in mind and aimed at safe water provision for domestic drinking use and thus focusses on life-long safety for all types of users (infants, pregnancy, breast-feeding and adults) and aesthetic acceptability.
These aspects are not necessarily relevant to intensive animal production systems where variable exposure periods and requirements to meet genetic potential under the production conditions require a very different emphasis.
By way of comparison it may be observed that whilst the SANS 241 Standard provides a statement on safe drinking water it is also not intended to provide appropriate fluid replacement for people engaging in athletic activities.
The DWAF guidelines for livestock watering, and the SANS 241 Standard, do not provide appropriate current guidelines given the failure to accord with the trends noted for domestic use above.
The next logical step to complying with the SAPPO statement would be to review international guidelines, but there too, problems exist. Without providing an exhaustive technical description the key problems are that guidelines tend to be formulated for local conditions with the WQCs listed largely a function of what is routinely detected in the local geochemistry and local laboratories.
As many South African pig production systems rely on subterranean water it is essential to include a comprehensive constituent assessment as this is influenced by local geochemistry. This is also true for domestic use with over 280 towns and thousands of rural communities relying solely on groundwater in South Africa.
In this regard international guidelines can be very misleading as they tend to focus on the constituents relevant to their particular set of local circumstances. One only has to note the numerous different types of mines operating in South Africa to gain some insight into the potential for geochemical anomalies to enter the subterranean water and drinking water supply.
Many of these guidelines also contain limits set over two decades ago with many analytical detection limits and research publications having subsequently identified additional WQCs relevant to assessing water quality. It is thus not surprising to observe the stated guideline limits to vary significantly between various published guidelines and recent scientific literature.
An example of this may be found when comparing the DWAF (1996) guideline for selenium in domestic drinking water with the SANS 241 2006 and 2011 editions. The DWAF guideline set the target water quality range for selenium at 0.02 mg/L as did SANS 241 (2006) classifying <0.02 mg/L as the recommended operational limit, whilst the current SANS 241 (2011) has reduced this by 50% by setting an upper limit of 0.01 mg/L.
The DWAF (1996) guidelines for livestock watering were also provided for general classes of animals, such as ruminants and monogastrics, whilst subsequent research for the Water Research Commission has produced hazard and risk assessment methodology for more specific categories of animal production, including commercial, rural communal and wildlife enterprises.
Water quality guidelines
As a brief indication to the norms and types of effects relevant for determining the fitness for use of water for intensive pig production systems the following may be considered relevant:
• Health: Toxicology
• Product quality:
Fitness for use for consumption
• Production system:
Water system effects
Application of water treatments
• Environment: Effects of animal and production system
Whilst this is a convenient agriculture-specific classification, in reality other recognised water uses are often also applicable, specifically for large scale agricultural enterprises. This includes water utilised by staff (e.g. drinking, food preparation, bathing and laundry), water for disinfection processes (e.g. chlorination and UV applications), industrial processes (e.g. heating and cooling processes) and effluent treatment for discharge compliance.
The relevant norms, types of effects and guidelines applicable are presented in later articles.
Water use and discharge:
Many legislative publications regarding hazardous waste can be found to have some application and/or derivation from confined animal feeding operations. It is therefore not surprising to find recent publications drawing attention to the potential hazards on the environment from waste derived from intensive pig production systems. A recent example of this may be found in the paper by Payet et al (2010) detailing nitrate pollution sourced from pig effluent.
Numerous documents may be found on the US EPA website describing the assessments required by confined animal feeding operations in order to comply with legislation pertaining to the US National Pollutant Discharge Elimination System. The term “pollutant” is not restricted to pig or animal manure or manure nutrients, but includes dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal and agricultural waste discharged into water.
The various discharge permits applicable consider factors relevant to different animal production systems and a section that deals specifically with swine is also presented.
Several South African Acts are applicable to water use and discharge of effluent (e.g. National Water Act, Act 36 of 1998; Environment Conservation Act, Act 73 of 1989; National Environment Management Act, Act 73 of 1998). Recent amendments and in some instances specific municipal bylaws may be applicable.
In terms of the National Water Act one of the water uses that require registration includes “feedlots”. Although those obtaining water for animal drinking purposes from a bulk distributor or local authority do not need to register, the use of such water for feedlots is specifically excluded from this and such use would thus require registration. Similar provision is made for controlled activities relating to the use of water for irrigation of land with waste or irrigation with waste itself and discharging waste or water containing waste.
In order to comply with the various water use licenses water quality monitoring and assessments are required. It is equally beneficial to have monitoring data on water sources used and potentially impacted on in order to proactively manage the resource and demonstrate inherent quality and/or evaluate the effects of water use and discharge.
It is noteworthy that both the Department of Environmental Affairs and the Department of Water Affairs are increasing their focus on compliance and enforcement. It follows that the pig industry should actively engage with these Departments in order to allow for proper consideration of factors relevant to pig production systems.
Whilst the water quality specific issues will be dealt with in subsequent articles, the legal aspects have been addressed in the Legal Environmental Compliance Guideline Document produced by the PPP (Compliance Guideline for the South African Pork Industry: Vers 1 2011).
The focus on water for pig production systems uses is typically on volume or quantity with the consistency of supply and associated costs assigned priority.
However, with the recognition of water scarcity and increasing emphasis on water resource management, with various licences and permits applicable, it is increasingly argued that the management of water quality should receive similar attention.
The fundamental point of departure is that in order to manage water appropriately, the quality thereof must be correctly measured, monitored and allocated accordingly to various uses by either matching the inherent quality to the most suitable use, or alternatively by treating the water to the required quality for the intended use.
In order to accomplish this “fitness for use” is largely defined by the use of water quality guidelines. Thus, the use of water for agricultural purposes may require the application of different sets of water quality guidelines which include aspects that are independent of considerations specific to intensive pig production systems.
References available on request