We’ve already put together a guide about Earth’s fresh water resources and supplies.
However, in the guide below, we list and explain the different natural and man made sources of fresh water that we use across society.
Natural vs Man Made Fresh Water – What’s The Difference?
The key differences between the two might be:
Natural Sources Of Freshwater
Are usually naturally formed, and involve on some form of natural replenishment.
Natural replenishment is related to Earth’s hydrological cycle, where rainfall (along with snow and ice melt in some instances) refills these natural water sources.
Because they naturally replenish (via the hydrological cycle, rainfall, and runoff/inflow), they are sometimes referred to as ‘renewable water resources’.
Something that is worth noting about ‘renewable water resources’, is that only a certain % of rainfall might recharge surface water and groundwater sources.
bom.gov.au for example notes that in Australia: ‘… only a small portion of [total rainfall] becomes renewable resources. On average, 9 per cent of this rainfall becomes runoff and about 2 per cent becomes recharge to groundwater’
Man Made Sources Of Freshwater
Man made sources on the other hand may either:
– Involve man made construction to build a fresh water storage area (and can be replenished with rainfall)
– Or, involve some type of man made fresh water harvesting, generation or treatment/re-use process (which can take a number of forms)
So, man made fresh water sources have a significant human component, or, are more dependent on humans to store or provide freshwater.
Natural Sources Of Freshwater
The main natural sources of fresh water might be:
– Surface Water
– Groundwater (& Underground Aquifers)
Man Made Sources Of Freshwater
The main man made sources of freshwater might be:
– Water Recycling, Reuse & Reclamation
– Water From The Atmosphere/Air (& Atmospheric Water Generation)
– Dedicated Rainwater Harvesting & Collection
What Is Surface Water?
Surface water includes bodies of water that are visible on Earth’s surface, such as lakes and rivers.
Wetlands are also considered a surface water source.
How It Replenishes
Surface water mainly replenishes via direct rainfall, different forms of water inflow and runoff (from rainfall), and sometimes catchment areas and civil structures designed to funnel water into these water sources.
Groundwater (& Underground Aquifers)
What Are Aquifers & Groundwater?
Aquifers store groundwater.
Aquifers are made of a layer of rock and other material, such as soil, sand and gravel, that are able to either hold or transmit water (to wells and springs) underground.
Aquifers can be shallower and closer to Earth’s surface, or deeper and further away from the surface.
How It Replenishes
Aquifers can replenish naturally, or via man made processes.
– Natural Replenishment
Aquifers replenish naturally when rain, stormwater, and water from surface water sources percolates through the soil, and infiltrates through the permeable layer of material that stores water in the aquifer.
– Man Made Replenishment
Interestingly, ground water can be recharged by humans as well.
One way is by increasing the inflow of rainwater and stormwater to them with purpose built civil structures (that might catch a greater volume of water, be more effective as a catchment, or channel surface water to them)
Another way might be via ground water replenishment schemes. One example is filtering treated water through natural sands, and injecting it into an aquifer to mix with existing groundwater, which can then be used for different applications
Speed Of Replenishment
Groundwater aquifers are reported to take longer to naturally recharge/replenish than surface water.
In some countries, they may take 5 years or more to see a meaningful change in water levels (although, recharge rates may vary from region to region)
This may be much slower than the replenishment rate of some surface water sources.
Additionally, in some countries, groundwater volume may not always increase after rainfall like it does for some surface water sources
In some cases, the rate of replenishment of ground water sources may be much slower than the rate water is withdrawn from them. This may lead to the groundwater source depleting.
Factors like these can make groundwater less sustainable as a freshwater supply source than surface water sources in some regions around the world
Groundwater in different regions of the world may have issues with either salinity (Australia for example has salinity issues with some of it’s groundwater), or brackish water.
Global estimates put the volume of groundwater at around 13 times higher than the volume of all surface water, including lakes, rivers and wetlands.
However, groundwater resources are not always suitable for large-scale or long-term use [because] Recharge rates are typically very small compared to the volumes in the aquifer [and] Groundwater is often saline, which reduces its suitability for use.
What Is A Dam?
A dam is a man made structure, usually made from concrete and other man made materials, that is built across a surface water source like a river.
What A Dam Can Be Used For
One of the primary uses of a dam is to store freshwater in a man made reservoir, when water flows from an upper reservoir to a lower reservoir.
But, dams can also fulfil other functions such as controlling flooding, and even generating electricity (in the case of hydroelectric dams, and where there’s a turbine installed).
How It Replenishes
Dams are generally reliant on rainfall, and the surface water source they are built on/across to replenish dam capacity and dam levels.
A good case study of changing dam levels for a city is Cape Town’s dam levels before, during and after their most recent ‘water crisis’ event.
What Is Desalination?
We’ve outlined what desalination is, along with the different technologies used, and other relevant information about desalination in this guide.
As a brief summary …
Desalination is the man made process that converts different types of water with higher than average salt content, into fresh water.
It does this by removing salt and other unwanted components (like minerals, particles, contaminants, and pollutants) from the water.
So, it’s a method of freshwater generation, but it’s reliant on different sources of water as inputs, such as seawater, saline water, and brackish water (from groundwater, and surface water sources).
It’s also reliant on other things, such as energy, and the finances required to build and operate desalination plants.
There’s various types of desalination, and there’s many desalination plants in operation around the world.
How Much Freshwater Desalination Plants Can Generate/Produce
The freshwater generation/production rate is dependent on the designed capacity of the desalination plant – different plants have different daily and annual volumes of freshwater they can generate/produce.
Potential Pros & Cons Of Desalination
Read more about the potential pros and cons of water desalination in this guide
Water Recycling, Re-Use & Reclamation
What Is Water Recycling?
We’ve outlined what water recycling is, how it works, and other relevant information about it in this guide.
As a brief summary …
Water recycling is also called ‘Water Reuse’, ‘Water Reclamation’, ‘Wastewater Recycling’, and a range of other phrases.
Although water is naturally recycled in the hydrological cycle, the recycling of wastewater is a man made process that involves treating and filtering wastewater to a certain standard/quality, and re-using that water for a specific end use (either as potable water, or non potable water).
So, it involves the conversion of wastewater back into freshwater, and, different types and sources of wastewater can be used in the process (such as municipal waste water, industrial wastewater, agricultural runoff, and more).
Water recycling is dependent on the availability of wastewater as an input.
Water recycling and reuse facilities and technology are used in several cities and regions around the world.
How Much Freshwater Water Recycling Facilities Can Generate/Produce
Similar to desalination plants, different water recycling facilities and programs are designed to generate/produce different volumes of freshwater.
Potential Pros & Cons Of Water Recycling
Read more about the pros and cons of water recycling in this guide
Harvesting Water From The Atmosphere/Air (& Atmospheric Water Generation)
What Is Harvesting Water From The Air/Atmosphere, & Atmospheric Water Generation?
We outline what harvesting water from the air/atmosphere, and also what atmospheric water generators are in this guide.
As a brief summary …
Water can be extracted/harvested from the air passively, or actively.
Atmospheric water generators are an active form of extracting water from the air, and they can extract water from the air with multiple methods, such as cooling condensation, and wet desiccants.
AWGs require a power source to operate (whereas passive water from air harvesting methods don’t).
In order to be most effective or work efficiently, AWGs might be somewhat dependent on there being certain conditions, such as the air being more moist (rather than dry).
AWGs and harvesting water from air methods are not currently used on the scale that surface water, groundwater, desalination, or water recycling currently are to provide water for society.
How Much Freshwater Water From Air Harvesting, & Atmospheric Water Generators Can Generate/Produce
It depends on the machine or device being used.
With atmospheric water generators for example, each unit is designed to harvest and produce/generate different volumes of water.
Potential Pros & Cons Of Harvesting Water From Air, & Atmospheric Water Generation
Read more about the potential pros and cons of harvesting water from the air/atmosphere, and atmospheric water generation in this guide.
Dedicated Rainwater Harvesting & Collection
What Is Rainwater Harvesting & Collection?
It involves capturing and storing rainwater with man made rainwater harvesting setups.
Pumped, and gravity fed rainwater harvesting setups, are some of the different types of setups available.
Rainwater can be stored in a variety ways, such as in water butts, in above ground tanks, and in below ground tanks.
Rainwater harvesting is usually used on a private level in households, and sometimes commercially or industrially as well (on a larger scale).
Many countries and regions of the world collect or harvest rainwater in a number of ways.
Rainwater harvesting may also be restricted in some regions of the world – for example, some States in the US may currently have conditions imposed on rainwater collection.
Although, other States may promote or encourage it.
Read more about rainwater collection and harvesting in this guide.
How Much Water Can Rainwater Harvesting Supply?
It depends on the size of the rainwater storage units and areas, and ultimately how much water the rainwater harvesting/collection setup is designed to collect and also store.
Potential Pros & Cons Of Rainwater Harvesting & Collection
Read more about the potential pros and cons of rainwater harvesting and collection in this guide
What Is A Well?
A well is a man made hole that is drilled or dug/excavated into the ground to access water stored in underground springs or aquifers.
Therefore, they are reliant on these springs and aquifers for a water supply.
What Are The Main Sources Of Water Used Across Society?
The main sources of water used across society differ between individual cities and towns.
For example, one region may get most of their water from dams, whilst another may get most of their water from desalination and groundwater.
A city or town may use multiple water sources for their water supply.
What Is The Main Source Of Water In The US?
It differs between the individual States, but, there may be a reasonably equal split between surface water and ground water on the national level (with surface water coming in slightly ahead)
Nrdc.org indicates that most of the public supply tap water in the US comes from surface water sources:
Surface water from freshwater sources … accounts for more than 60 percent of the water delivered to American homes
Nearly 40 percent of Americans rely on groundwater, pumped to the earth’s surface, for drinking water [and] For some folks in rural areas, it’s their only freshwater source
water.usgs.gov indicates that ‘[In 2010, of the total 306,000 Mgal/d (million gallons a day) of freshwater the US withdrew, 230,000 Mgal/d cam from surface water, and 230,000 Mgal/d from groundwater]
State & City Level
worldatlas.com indicates that different cities and States within the US get their drinking water from different types of sources such as lakes, rivers, reservoirs, aquifers, aqueducts, and so on.
What Is The Main Source Of Water In The UK?
Most of the tap water in the UK might come from surface water sources
… surface water [such as reservoirs, lakes, and rivers] accounts for 68% [of tap water in the UK] …
About one third of tap water in England and Wales comes from underground sources (aquifers) …
What Is The Main Source Of Water In India?
India might be one of the world’s largest groundwater users
In urban India, at least half of the water supply might come from groundwater sources
In rural India, groundwater use might be much higher
India is one of the major ground water users in the world [with] India [using] 25% of all groundwater extracted globally, ahead of the US and China
In urban India, 50% of the water supply is groundwater-based
Some 90% of rural India’s drinking water comes from groundwater and 75% of agriculture is groundwater-based.
What Is The Main Source Of Water In Australia?
On a national level, most of Australia’s water supply in urban areas might currently come from surface water sources
On a State, Territory and city level, different water sources make up different %’s of the water supply in different geographic locations
The bom.gov.au report indicates that: ‘… cities mostly rely on ground water and surface water … [with] One-fifth to one-third of the water used in Australia comes from groundwater’
State, Territory & City Level
theconversation.com has a graphic that shows what water sources Australia’s major cities currently get their water supply from
bom.gov.au also provides information on the major water sources in the major Australian cities in their report (on page 51), and we’ve summarised these water sources in this guide
Perth in Western Australia is an example of a city that currently gets most of their water from desalination, followed by groundwater.
1. Various ‘Better Meets Reality’ guides