1.10: Recycled Water, Reuse, and Conservation
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Water is one of our most precious and vital resources on earth. Without it, life would not exist. However, at times we all take water for granted. Every time we turn on the faucet at home water comes flowing out. We have learned throughout this text where water comes from, how it is treated, and how it is distributed. We also learned about the hydrologic cycle and how water is transformed from one phase to another. But, what if part of this hydrologic cycle is interrupted? What if it doesn’t rain? What if there is no snow in the mountains? In 2011 – 2015, California was faced with one of the worst droughts in the state’s history. California has seen record low snow pack in the Sierra Nevada Mountains and historically low rainfall throughout the state. In January 2015, San Francisco recorded no rain for the first time in the city’s history. The Governor and the State Water Resources Control Board handed down mandatory conservation regulations in 2015. Some water suppliers were asked to conserve as much as 36%. What if droughts continue for long periods of time? Will conserving water be enough?
Conservation is always a prudent approach to saving water, but sometimes it will not be enough to offset the potential loss of water during times of serious drought. Reuse is a term used often in the water industry to identify reusable sources of supply. Recycled (reclaimed) water is one of the most common reuses of water.
“Recycled Water” can be classified as any water which is reused and has not been processed for drinking purposes. For example, if you have a rain barrel and you collect rain water and use it to irrigate your yard; this can be thought of as a type of recycled water. Storm water runoff can also be looked at as a type of “recycled water.” As it rains and storm water is captured and reintroduced into a groundwater basin to recharge, an aquifer can be considered a form of recycled water. Greywater systems are also a form of recycled water. Grey water is the water collected after uses such as dish and laundry washing machines and reused as irrigation water. Although these previous examples can be thought of as “recycled water”, most people think of recycled water as treated wastewater. Wastewater is solid and liquid discharges from all sources dumping into a municipal sewer system. Sometimes, storm water can enter a sewer system through manholes in a street. However, most storm water makes its way through a storm drain system and eventually flows to the ocean. This water is typically untreated. In contrast, wastewater goes through a series of treatment processes to remove solids, harmful pathogens, and other things to make it acceptable to be discharged back into the environment. The various wastewater treatment stages are referred to as primary, secondary, tertiary, and advanced treatment. Most wastewater used for recycled water purposes goes through at least tertiary treatment. Below is a brief description of each wastewater treatment process. These processes are covered in more detail in the Water 060 and 061 courses.
- Preliminary Wastewater Treatment - The removal of large, entrained, suspended or floating objects. The treatment process usually consists of large screens and cutting devices.
- Primary Wastewater Treatment - The separation of solids and greases through settling tanks and clarifiers.
- Secondary Wastewater Treatment - This step involves the removal of organic matter primarily through biological treatment.
- Tertiary Wastewater Treatment - Disinfection chemicals such as chlorine and ultra-violet light are used to remove pathogens (disease causing organisms) from the wastewater.
- Advanced Wastewater Treatment - If additional contaminants need to be removed sometimes advanced treatment is employed with the use of membrane filtration and/or additional chemical treatment processes.
When discussing recycled water the main purpose is to reduce the burden on fresh water supplies by reusing water such as treated wastewater. Recycled water is commonly discussed in unison with water conservation. The idea is to Reduce the amount of water used, Reuse water supplies for various purposes, and Recycling treated wastewater. The remaining sections of this chapter will discuss these “conservation” related topics and how the three “R”s are incorporated.
Groundwater recharge is the process of water from the surface re-entering the ground becoming groundwater. Typically groundwater aquifers are recharged through precipitation. Rain and melted snow makes its way to an aquifer recharge zone and percolates deep into the soil becoming groundwater. However, there are other sources of water which can makes its way to a recharge zone can become groundwater. For example, if a fire hydrant gets hit and water flows into a storm drain which discharges to a dry riverbed with an underlying aquifer can percolate into the soil becoming groundwater. Another example is the treated effluent from a wastewater treatment plant. These types of examples are referred to as “incidental” recharge.
Direct Potable Reuse
Direct potable reuse is using a source of recycled wastewater directly as potable water. At the time this text was written, this is not an approved source of potable water. There are too many health concerns and unknowns regarding the quality
Indirect Potable Reuse
Indirect potable reuse is the process of reusing treated wastewater to recharge groundwater basins and aquifers and to augment various surface water supplies. This type of reuse can be something which is termed “incidental” or it can be a planned and constructed use. Anywhere wastewater is treated and discharged back into the environment has the potential to recharge an aquifer. For example, if a wastewater treatment plant is discharging into a dry river bed and this dry river bed has an underlying groundwater aquifer, this would be considered incidental recharge. If there are groundwater wells downstream of this discharge location, this “incidental” recharge would be a potential supply for these wells. Conversely, in Orange County, CA there is the Groundwater Replenishment District which takes highly treated wastewater and pipes it back up into the groundwater basin for recharge. They process enough water to serve approximately 600,000 people.
There are however, several challenges when presenting these wastewater reuse strategies. Professionals within the water and wastewater industries have a good understanding of the various treatment and distribution processes of water making it safe and reliable for human use and for the environment. The general public typically has less of an understanding, especially when it comes to reusing wastewater. This lack of understanding usually results in a reluctance of the public. When terms as “toilet to tap” are floated around the media, the public becomes skeptical. In addition to perception, there is a significant cost which goes along with all reuse options. A significant amount of infrastructure is needed to bring water from wastewater treatment plants to the various customers. Many times miles of pipeline is needed as well as pumps and storage. The infrastructure costs can often times be cost prohibitive. However, in new developing communities, the infrastructure costs can be greatly reduce by charging connection fees to developers and because it is much cheaper to install pipe lines in dirt than existing streets in asphalt.
There are multiple reasons why recycled water should be used. Since water can be a limited resource in many parts of the world, recycled water can be used for many different non-potable uses where potable drinking water is typically used. For example, an office building can be “dual-plumbed” so the restroom water for toilets is recycled water and the sink water is potable drinking water. By far, the most common use of recycled water is for irrigation. By using recycled water we reduce the reliance of fresh water from sensitive ecosystems, reduce the dependence on importing water, and there is the potential for energy savings by reusing a local resource. These are just a few examples of recycled water uses and benefits from reusing treated wastewater. In addition to the public and costs issues with using recycled water, there are various permitting hurdles with Los Angeles Regional Water Quality Control Board (LARWQCB) and Division of Drinking Water (DDW). The LARWQCB is responsible for promulgating the federal Clean Water Act. As part of this act, it gives the authority of maintaining clean water in what is called “navigable waters of the U.S.” Locally, a navigable water of the U.S. would mean the Los Angeles River and the Santa Clara River. All water discharged into these and other water bodies must meet certain water quality standards known as Basin Objectives. Each watershed can have different water quality objectives depending on the beneficial use of the water in the watershed. Since DDW is responsible for drinking water systems in California, they oversee recycled water use and water used for groundwater recharge. Their requirements involve the quality of the water and how long the water being discharged and subsequently pumped out through groundwater wells for domestic use. In addition, the agency responsible for treating wastewater may also have specific regulatory requirements. In Los Angeles, this would be the Los Angeles County Sanitation District. LA County Sanitation District has permits with the Regional Water Quality Control Boards for discharges and they have also set up specific requirements to use their treated wastewater as recycled water. These and other rules and regulations are not limited requirements, but they do require time for research, analysis, and permitting before recycled water can be used. Below is a list of some of the approved recycled water uses.
- Groundwater Recharge – certain LARWQCB and DDW rules and regulations apply. For example, the quality of the water used must meet certain LARWQCB Basin Water Quality Objectives and the quality and distance before the water is pumped out of the ground for domestic use must adhere to certain DDW regulations.
- Lavatory Facilities – if the plumbing system of a building is “dual-plumbed”, meaning there are pipes specific for different uses, recycled water can be used for toilets, drainpipe priming, etc. There are specific DDW rules and regulations that apply. Currently (2015) dual-plumbed systems are not allowed in residential homes.
- Industrial and Commercial – certain business processes can use recycled water for non-potable purposes. Various regulations apply.
In addition to the regulatory requirements mentioned above, some of the specific requirements imposed on water suppliers before they can began using recycled water are the following:
- Users must have a Site Supervisor. The water supplier is required to coordinate with the user training and assignment of an onsite supervisor.
- Annual visual inspections must be conducted. The Site Supervisor and the water supplier must coordinate these inspections.
- Pressure test inspections are also required every four (4) years. In addition to the Site Supervisor and water supplier, a State or County Health Department usually provides an inspector.
Locally in the greater Los Angeles area Valencia Water Company, Burbank Water and Power, and Los Angeles Water and Power serve recycled water.
Why should we conserve water? There are a number of reasons why someone would conserve water. During times of drought there may be regulatory requirements for water conservation. Some people may think it is just the right thing to do since water can be a limited resource in certain parts of the world. Or, maybe you just want to try and save a little money. Water rates are always getting higher and higher and the less you use, means the less you will pay. Reusing water, whether it is recycled water for irrigation or recycled water used to recharge groundwater aquifers, is a prudent approach when it comes to water resources. However, water conservation or reducing the amount of water used is also an important tool when it comes to water supply resources. Reducing the amount of water we use will help ensure the availability of water in the future. As the cost of water continues to rise, it is also economically prudent to reduce the amount of water used.
In 2009, the governor of California signed into law Senate Bill x7-7. This bill is also known as 20x2020 and requires all water suppliers to reduce their water demand by 20% by the year 2020. The 20% reduction is calculated using the water suppliers average customers daily use or gallons per capita per day (gpcd). Gpcd is calculated by taking the total water production and dividing it by the total population.
Daily Production = 9,600,000 gallons
Total Population = 40,000
9,600,000 gallons / 40,000 people = 240 gpcd
A 20% reduction for this example would equate to a 192 gpcd. In this example, you might be thinking that this is a lot of water for one person to use in one day. However, if you recall from the Water Use chapter, the amount of water used can add up quickly. Regardless of the reasons you decide to conserve water, the bottom line is you will save money.
Let’s go back to the 20% savings example above. A 20% daily savings of 48 gpcd for a family of four (4) will equate to over 70,000 gallons a year. Let’s take a look.
48 gpcd x 4 people = 192 gallons per day.
192 gallons per day x 365 days = 70,080 gallons per year
Most utilities bill in hundred cubic feet (HCF or CCF) billing units
1 CCF = 748 gallons 70,080 gallons / 748 = 94 CCF
Now, we need to make an assumption how much a water supplier would charge for a CCF. Water rates vary, but averages in the southern California area range between $1.60 - $3.50 per CCF. Therefore, using the low and high of this range, this family of four (4) would save
94 CCF x $1.60 = $150.40 per year 94 CCF x $3.50 = $329 per year
I don’t think anyone would turn down $150 a year let alone $329! So, regardless of the reason you might decide to conserve, there is the potential to save a lot of money.
How Do Water Suppliers Get Customers To Conserve?
Sometimes people are not aware of how much water they use. They might look at their monthly water and if it looks similar to the month before they do not think twice before paying their bill. Communication is the number one tool water suppliers have at their disposal to promote water conservation. Bill inserts, flyers, social media, and all good ways to communicate to the public about conservation. Some water suppliers may also use billboards and radio and television advertisements. Getting the word out is the first step. Many water suppliers offer a variety of incentive rebates to help people conserve water. Low flow toilets, efficient appliances, drip irrigation nozzles, and “turf” buyback programs are just a few rebate programs water suppliers use.
Sometimes water suppliers need to take a more aggressive approach, especially if there is a drought and regulations require conservation. If the public does not respond to outreach programs or rebates, utilities will often resort to increasing water rates and/or issue fines. This is not the most popular approach among customers, but sometimes it is a necessary tool to force customers to conserve water. It is also important to note that sometimes water suppliers will have to increase water rates because of conservation. The less water used means the amount of revenue a utility collects will decline. This is probably one of the most difficult things to communicate to customers. Water suppliers tell customers to use less water and then the water rates are increased anyway.
One of the last things a water supplier will use to get customers to use less water is to shut off their water service. This is not usually advisable, because a minimal amount of water is needed to maintain health and safety, but at times, people might have their water service discontinued for a certain period of time until they decide to use less water.
There are various different rates structures water suppliers use. They include; flat rates, uniform single quantity rates, tiered rates, and water budgets. The type of water rate a utility will use is dependent on a number of factors and vary for area to area.
Flat rates are the simplest rate design. The rate is the same or flat for every customer regardless of water use. This type of water rate is common in areas where use is relatively the same for everyone. For example, an area where outdoor irrigation is not needed because of ample amounts of precipitation and indoor use is the predominant use a flat rate might be used. However, some people might deem this type of rate unfair because a large family would essentially pay the same amount as a single person living in a home. This is a very easy rate structure for utilities. No meters are needed and the revenue amount every year is relatively constant.
Uniform Single Quality Rate
This type of rate structure is considered a more fair way to charge for water and the services associated with treatment and delivery. There is a single rate price for one unit of water. Therefore, if you use one unit (CCF) you only pay for one unit of water. Whereas if you use 100 CCF of water you pay for the 100 CCF you used. It is probably the most common rate structure. Each utility with this rate structure must make sure they review the income revenue often since a large reduction in use will translate to a large reduction in revenue. The amount of money a utility needs to operate is referred to as revenue requirements. This will be reviewed later in this chapter.
Tiered rates are becoming more common, especially in areas where use patterns can fluctuate, such as areas affected by drought. This type of rate structure can be used to encourage conservation. The cost of a unit of water increases the more you use. There can be as few as two tiers and some agencies have up to five tiers. A tier rate structure might look something like this;
Tier 1 = $1.50 per CCF up to 10 CCF (1 – 10 CCF)
Tier 2 = $2.00 per CCF for each unit over 10 CCF up to a certain amount (11 – 20 CCF)
Tier 3 = $3.00 per CCF for anything used over 20 CCF (21 and up)
Let’s see how this type of rate structure works. The following example is based on a monthly water usage of 30 CCF. The first 10 CCF of the monthly 30 CCF usage would be billed at the $1.50 per CCF rate. Therefore, you would multiply 10 CCF by $1.50.
10 CCF x $1.50/CCF = $15
The remaining CCF would be 20 (30 CCF - 10 CCF). The next 10 CCF of water used (11, 12, 13…20 CCF) would be billed at the second tier rate of $2.00 per CCF.
10 CCF (11 - 20 CCF) x $2.00/CCF = $20
The remaining usage up to 30 CCF is another 10 CCF. These remaining 10 CCF (21, 22, 23…30 CCF) would be billed at the third tier rate of $3.00 per CCF.
10 CCF (21 – 30 CCF) x $3.00/CCF = $30
All three total charges would be added together for a total monthly bill amount of $65.
$15 + $20 + $30 = $65
This is a very simplistic look at a tiered rate structure, but it should illustrate how the cost of water increases based on the amount used. You can see how this type of rate structure might encourage conservation.
The last rate structure we will look at in this text is called water budgets. It is a similar structure to tiered rates. However, unlike tiered rates, water budgets provide a more fair and equitable way of charging for water use. In a straight tiered rate structure many people complain because of the subsidization issue. Large use customers pay much more and in some instances subsidize smaller users. This is because a traditional tiered rate structure is blind to parcel size. Water budgets are different. A water budget is an individualized rate structure based on each customer’s specific parcel. For example, a customer with a large yard and multiple people living in their home will have a larger budget than a single person living in an apartment with no outdoor landscaping. Both customers would have a monthly allocation specific to their needs. Water budgets usually classify an indoor allocation of 50 - 60 gpcd and then specify an outdoor allocation based on actual landscape measurements or perhaps a percentage of the parcel size. All this information gets input into a formula to calculate the monthly budget. The formula typically includes a monthly evapotranspiration rate (ETo) and a coefficient for the specific type of landscape material. The evapotranspiration rate is the amount of water needed to sustain plants based on the current weather. For example, the ETo rate is higher in summer months than during the winter. Although this is a more equitable rate structure, it does require additional work by the water supplier and can sometimes be confusing for customers to understand.
Regardless of the rate structure, the utility must demonstrate that their rates are truly the cost of providing service. There have been lawsuits in the past and will continue in the future, challenging various rates structures and the amount being charged. Utilities must adequately identify why their rate structure is the needed amount for their specific revenue requirements.
One last rate component should also be discussed. A service charge is a monthly (or bi-monthly) charge placed on each customer regardless of the amount of water used. This charge is a flat rate and covers some specified percentage of the water supplier’s revenue requirement. It is sometimes referred to as a “readiness to serve” charge. It guarantee’s a certain amount of revenue every billing period allowing the utility to continue basic business functions without worrying about usage fluctuations.
This term has been mentioned several times in the preceding sections. A revenue requirement is nothing more than the amount of money (revenue) a utility must collect to maintain their basic day-to-day service. Water rates and service charges are the primary source of revenue water suppliers receive. Well, what is a “revenue requirement”? A water supplier has certain expenses, which cannot be avoided. For example, water treatment is required in order to provide a safe drinking water supply to customers. For each gallon of water served it requires a certain cost for treatment. Likewise, there are electrical costs for pumping water, maintenance costs, salaries and benefits for employees, and costs for replacements and improvements to infrastructure. There a many expenses to operate a water utility, but this doesn’t mean there is no room to reduce costs to keep rates low. Each water supplier must determine what is necessary and what can be reduced or cut in order to maintain an efficient operation.
Water is a vital resource and the availability of fresh water varies throughout the world and is dependent on weather patterns. An El Niño weather pattern can bring much needed rain to parts of the world while creating devastating droughts in other parts. Understanding the use and need of water will help us all use it a little more wisely and will help professionals manage this important resource. There will always be a need for water professionals as long as clean, safe, and reliable drinking water is needed.