The perception of a service provided can be obtained using subjective surveys based on the population's physical, economic and social characteristics. This study focuses on the use of standardized surveys to obtain users' perception of a drinking water service, as well as measuring domestic consumption with water meters and pressure data, using specialized recorders to identify daily patterns in water use and consumption. Factors can be identified indicating drinking water use patterns among the sector's inhabitants throughout the day, week and month, and taking climatic factors into account, by analyzing consumption habits and the related measurements. An important point that is defined is the demand factor, to indicate key points in estimating existing and future demand based on an intermittent supply. The study includes a proposal for a management model based on the demand factor, with which the sector's consumption needs are solved and drinking water supply is efficient. The results obtained gave us an overview of water losses, awareness of the value of the drinking water service, and the users' interest in taking care of it.
Standardized surveys to obtain the perception of users of a drinking water service.
Identification of water use patterns.
Analysis of consumption habits with metering.
Defined demand factor indicating existing and future demand based on intermittent supply.
Proposed water management model.
Increasing population density and the dynamics of urban expansion, with a marked tendency towards growth of urban areas and decreases in rural populations, make megacities focal points of vulnerability and high complexity in the provision of basic urban services (Escolero et al. 2016).
Water consumption is determined by many variables including: climate (temperature, rainfall, relative humidity), social factors (number of inhabitants per dwelling, family composition, education level, social stratum), economic factors (household income, water price, historical consumption) and/or cultural factors (people's lifestyle, values, norms and social models, beliefs associated with environmental behavior), which will have different relevance depending to context (Manco Silva et al. 2012). Estimating drinking water demand correctly is very important in supply system planning and design, which largely determines both the investment necessary and the quality of service (Tzatchkov & Alcocer-Yamanaka 2016).
Several cities do not currently have 24-hour drinking water services and can supply their populations intermittently at certain times of the day. Intermittent supplies are used to ease the supply drinking water to a population with accelerated exponential growth where the necessary infrastructure to meet full demand is not available.
Constant population growth and the need to meet demand to satisfy their basic needs requires management strategies that promote efficient water use – e.g., legislation and regulations, tariffs, information and/or education campaigns, and/or implementation of new technologies and infrastructure control (Manco Silva et al. 2012).
The Riberas de Sacramento area currently has an intermittent potable water supply. The pipes are, however, pressurized a minimal level, during non-service hours to avoid the transitory effects of air and the resulting damage. The pressure is raised sufficiently to fill a reservoir and meet basic hygiene needs on a fixed schedule. It is intended, in this way, to achieve a continuous service eventually to meet users' full demand.
Data collection was carried by interview using a questionnaire about household characteristics such as family income, number of inhabitants and monthly water consumption, and the degree of satisfaction with the existing water service, the importance of the drinking water service for each user and the different uses that each gives to water in their daily activities (Blanchet 2021).
A representative sample of the total population of RDS was surveyed. The survey was based on a previous study of the general characteristics of the sector.
Data collection from the ultrasonic meter lasted seven days, with cumulative recording every 15 minutes.
The study was conducted at various times from September 2020 to February 2021.
After the collection of consumption and pressure measurement data, and survey responses, the data were analyzed using graphs, pattern trends and value exponentiation. In this way, it was intended to infer predetermined behavior based on the sector's user characteristics and the measurement data that reflected the likely behavior of the population under study (Díaz 2001).
The results (Figures 3 and 4) are interesting with respect to the sample population's characteristics. When compared with the country's average, the study data show some differentiation of the people of RDS from the national average.
Individually presented each of the questions with their analysis, the following could be inferred:
How many people live in your house?
The average number of occupants per dwelling in 2020 was 3.2 (INEGI 2020), for this research the number of people living in the house was between 3 and 4 people, which gives an average of 3.5, this reflects an area with a higher number of people in housing than the national average.
Do you have a potable water storage system?
The most common type of storage is the water storage tank, which indicates that the drinking water service is provided in a sufficient and adequate manner. The reservoir in a home reflects the efficiency and effectiveness with which the operating agency supplies sufficient water for the needs of users, and if it is not available, it could be considered a basic service.
Do you consider the quality of the water that reaches you to be adequate?
Most users responded that the water quality is adequate, which reflects a fundamental condition to prevent and avoid the transmission of gastrointestinal and other diseases.
What problems have you detected with respect to water quality?
The taste and odor of the water are detected through the senses and the color and turbidity in a qualitative way. The result of this question indicates a majority of users in the range of not perceiving any discomfort in water quality, although there is a slight percentage that does perceive discomfort, which should be further analyzed to rule out a local problem.
Do you drink water directly from the tap?
Although users generally perceive the water they receive to be of good quality, the water they say they use for drinking is not tap water.
Do you consider the amount charged on your bill to be fair?
The sum of the positive responses shows a majority in this item, indicating that the collection of the water bill is satisfactory for the most part among the population, although there are some objections by nature.
How much water (liters) is regularly charged per month?
Between 200 and 350 Mexican pesos is the value that most of the users express that they are charged a monthly fee. Taking this fee into account to calculate the monthly volume and the population's water supply based on it results in a water supply of 190 L/inhab/day and a monthly volume of 21 m3.
Do you consider that you have sufficient water pressure?
Considering that an acceptable pressure to supply a home with drinking water is 1 kg/cm2 and that most of the users responded to this question that they always receive water with sufficient pressure, it was possible to confirm the good drinking water service in the area.
What problems have you detected regarding water pressure?
Although there were responses in the various categories, the one that stood out the most and highlighted satisfaction with the service was ‘no problem’.
How many hours of pressure do you have per day?
Although most of the users answered that they have drinking water service from 6 to 8 hours, it was possible to intuit that there is an area with a problem of leaks or hydraulic deficiency for the considerable range of 2–3 hours, which represents a problem to be able to satisfy the user's needs in a greater number of hours.
Do you maintain your water tank or cistern?
It was possible to confirm that most of those surveyed do pay attention to the storage system, but they do not have a scheduled date for this. Despite this, a certain number of users do not clean their tanks, which presents a health risk due to the bacteria and viruses that develop in this environment.
Does you water tank/cistern receive water from the public supply?
Most of the users responded that their water tanks are always filled, but there is a small percentage of users who do not, which suggests that they do not have good service. Once again, we reiterate the need to probe the areas where the water tanks are not filled due to a possible incidence of undetected leaks.
Does air come in through your water supply pipes?
Most of the users responded that they do not receive air through the pipes, but since there are users who responded that they have air in the pipes, it is necessary to check for a possible hydraulic problem in the area, such as lack of ejector valves or deficient minimum pressurization pressure in the pipes during off-hours.
Do you check that the water meter readings agree with those shown on the bills?
The results of the survey show that the largest number of users answered ‘never’, which reflects the fact that no failure is detected on the part of the user to operate their meter or their monthly consumption amounts.
Do you check your water meter for leaks?
In the results of the survey, the highest percentage was very satisfactory, since most of them always verify that there are no leaks, that is, that there are no leaks in the household meters in the study area.
Do you check for leaks inside the house?
‘Always’ presented the highest percentage of response for this question. An inspection of this type is important to avoid surprises of high service charges, as well as damage to the architecture of the home.
If a leak is detected in the water pipes, is it repaired quickly?
The highest percentage was determined with the response ‘Always’, which is indicative of the fact that the agency attends to the leaks reported by users in a timely manner.
What is the air conditioning system you have in your home?
Most of the users have a cooling system, which reflects the need of the users to have a system that provides the capacity to regulate the ambient temperature since they live in a semi-desert area and this involves a very high ambient temperature during the summer.
Do you use air conditioning?
It turned out that almost half the users did not use air conditioning. This reflects how the temperatures this season were not so high and allowed them to survive the heat without the need to turn on the air. It is also a reflection of the general cost of turning on such a device and the energy consumption it generates, to which users of the sector prefer to keep it off to avoid generating high energy bills.
In what seasons do you use air conditioning?
According to the results of those who have a conditioning system, the highest percentage was presented to use it during the summer. This confirms the most unfavorable time of the year for users.
Does the bill increase when air conditioning is used?
The users responded that the bill does not increase when using the air conditioner. This question is inferred from the fact that an evaporative air conditioner adds a large amount of water that impacts the user's bill, but the user's response is not consistent since they do not detect an increase in the service charge despite turning on the air conditioner.
Are there people in the house at all times?
In this question, if we add the answers of the users ‘sometimes’ and ‘always’, a majority result was obtained, with the highest percentage of users answering ‘always’. And the rest of the surveyed users, with answers: ‘never’, ‘few times’ and ‘lot of times’.
Does everyone in the household use the shower every day?
A large number of users answered ‘always’ and ‘sometimes’; adding these two answers together, it appears that almost all of them do use the shower every day. This is indicative of a routine daily consumption of drinking water.
Does each person's shower last less than 10 minutes?
The response was found to be almost equally divided so half the population is considered to last less than 10 minutes and the other half more than 10 minutes.
Do you water or wash the garden or yard?
Again, this question has split answers, with practically half the population watering or washing the garden, but the other half not doing so, which leads us to a split consumption for this activity.
Do you wash clothes in the washing machine and/or laundry room?
‘Always’ and ‘sometimes’ were the most frequent responses. This indicates that there is a constant use of water for washing clothes and it can be considered as a basic routine consumption of the users.
Do you flush the toilet handle immediately after use?
‘Always’ was the answer that received the most votes, reflecting the neatness with which the sector's users handle themselves and how this concept should be considered with basic routine consumption.
Do you wash your hands immediately after using the toilet?
Hand washing can keep you healthy and prevent the spread of respiratory and diarrheal infections from one person to another. 100% of respondents always wash their hands after going to the toilet.
Do people in your house turn off the water when not in use when brushing their teeth?
It can be observed that the highest percentage of users in the sample answered ‘always’. This represents data that can be disregarded from the high consumption.
Do people in your house turn off the water when not using it to wash the dishes?
The highest percentage of the users in the sample answered ‘always’, the only thing missing was to ask how many times a day and how long they wash the dishes in order to correlate with high water consumption due to the amount of time invested in this activity.
If the people in your house see a faucet open or leaking, do they turn it off?
4,000 drops make one liter of water, which is why 100% of the surveyed users responded that they do turn off the faucet when a leak occurs.
Do you avoid playing with tap water?
100% of the users always avoid playing with tap water. This reflects the cultural education in the area and respect for water and its care and use in the best way possible due to the semi-desert climate in which they live.
Do you wash the vehicle with tap water?
If it is used in a container when cleaning the car, it can use up to 50 liters of water, but if the car is washed with a hose, the amount can reach up to 500 liters of water. This is why it was found that the population is aware of the high consumption of tap water, so most of them answered that they never wash the car with tap water.
When washing the vehicle, do you use less than 40 liters of water (2 buckets)?
A peculiar characteristic of the users was reflected here, which is that not all users have their own vehicle, and that is why they do not consider it relevant to use a certain amount of water to wash a vehicle, since they do not have a vehicle at all.
Analysis of the surveys enabled a first approach to the users, whose participation was important. The results gave an overview of water losses, as well as the water service's value and users' interest in taking care of it.
Water is very important. If the service is intermittent, home storage is needed. Details of the household are needed to determine the storage capacity required. In RDS, with its intermittent supply, storage tanks are needed, and 96% of those surveyed have them.
In the analysis of the data on continuity of supply, several aspects must be taken into account: daily or weekly discontinuity causes a reduction in supply pressure and, therefore, increases the risk of contamination in the pipeline. Other consequences are reduced availability and use of a smaller volume of water, which adversely affects hygiene. It may be necessary to store water in homes; the storage and handling of the corresponding water increase the risk of contamination.
The water supply can be affected by contamination due to leaks in the network, etc. Continuous, pressurized, piped water supply services are subject to low and high pressures at times. Seasonal discontinuity may also force users to be more wary, because poor quality water is detected sometimes in some areas.
The results from the questionnaire showed that the sector is middle class taking in count the amount they consider to pay for the water bill and it was not necessary to ask users for their specific income on account of the impoliteness of doing so. Some 47% of those surveyed have sufficient income to cover comfort expenses. If the service deficiencies identified by users are addressed, and the users see the service improvements, there is the capacity to pay.
It is clear, therefore, that it is important to understand the population's water consumption habits and the factors influencing them.
With respect to the analysis of consumption and pressure data to obtain characteristic patterns of the sector, the importance of the result is noted, since by using this pattern, it will be possible to infer the possible general behavior of the sector in a continuous service that takes advantage of the schedules and the resulting consumption values to meet the needs of the sector's users.
An example of how obtaining this factor of demand helps to infer future behavior or needs of the population is through the comparison of the demand obtained in the graph of average pressure and demand, where to obtain that you have up to 70 L·s−1 and a pressure of 2 kg/cm2 is obtained inversely that the optimal pipe for the circulation of that flow is 6 inches according to the hydrodynamic theory of the square of the diameter of the pipe multiplied by the working pressure (Hernandez 2014), which gives us as a result the maximum expenditure to be able to circulate and so since the square of 6 is 36 and multiplying it by up to 2 kg/cm2 gives us 72 L·s−1, this covers the 70 L·s−1 that are needed in the fairest way.
Obtaining the consumption pattern gives continuity to the objective of this research, which is to analyze the current situation of an intermittent supply and take advantage of its characterization of consumption habits for the gradual implementation of a continuous supply of drinking water with pressure management.
The research shows the different perceptions of the drinking water service provided to the population, which in general is good since the results show a correct satisfaction with the quality of the water supplied, a pressure considered sufficient, little or no air in the water supply, an adequate collection of the service and a correct care of the use of drinking water, avoiding as much as possible the waste of it.
It is important, after perceiving the observations of the users of the sector, to analyze the consumption and pressure data available in the supply network to be able to infer future behavior and take it as a basis for possible sectors with similar characteristics.
In this case of RDS it was possible to detect with the measurements taken and after processing and analysis of averages and moving averages over 10 periods, that the sector has an intermittent supply but not completely, since the supply network is not completely discharged and this allows to continue pressurizing the water distribution networks to avoid breaks in pipes due to fatigue. Also, certain users in the lower areas have the possibility of continuing to draw water from the network, although in smaller quantities due to the lower pressure supplied.
It is by combining the values obtained from the consumption and pressure measurements that average pressure and consumption patterns are obtained, with which a 10-period moving average is calculated to provide a more stylized graph of the population's demand factor to correlate it with the current pressure supplied. This gives us a demand factor that will be used to estimate future demand in a sector with similar characteristics to the one being analyzed in terms of type of existing supply and actual quality of service supplied.
A proposal for a management model for the supply of drinking water to a given sector is based on obtaining consumption and pressure data from an area of similar characteristics and by means of its demand factor analysis to obtain the average consumption throughout the day for the variation in the opening of the flow so that more water reaches the homes when it is most needed.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conflict.