Throughout the first three-quarters of the 20th century, the quantity of freshwater consumed per person doubled on average.

Here, in the sentence. You can redesign sentences as per need. 

  Throughout the ...............of the ..............., the quantity of ................. consumed (utilized/ purchased/expended/  used/ demanded) per person doubled( triple or times or  times or unfold or so on ) on average ( more than half, near to average, constant, )

2

But since 1980, the amount of water consumed per person has actually decreased, thanks to a range of new technology)

Here, in the sentence, you can rewrite 

But since ........, the amount of ........ consumed (utilized/ purchased/expended/  used/ demanded) per person ( per age group/ per gender/ per social group/ any sorts of group) has actually decreased(Plunged/ plummeted/declined/dropped).

--Different Between squandering vs. Consuming?

3. At the outset to the new millennium

Just change the last phrase

 At the outset to ......

4. During the industrial revolution and population explosion of the 19th and 20 th centuries, the demand for water rose dramatically.

Below here is sentence to be replenished 

During the .............. and .............. of the ... and .... centuries, the demand for water rose dramatically.


Often I get confused with word 'Crematorium' 

Synonyms: Cremation chamber, crematory, 

The second wave COVID 19 variant has affected the hospitals operating capacity due to this death toll has risen up and  the crematorium felt difficult to manage death bodies. Meanwhile, the administration has accorded high priority to making available more oxygen supplies, amenities to hospital across the country.


3. As the sales of milk has plummeted due to the high prohibitory order imposed in major cities. The milk collection has dropped by around 25%.

another alternative way

As the sales ( purchase, demand, order, buy,) of ...has plummeted due to the .............. The .......collection has dropped by around ....

Vocabulary 

1. Entwine (v)- Entwined -Entwined 

Money plant will entwine round the stick as it grows. 

Frequently, the lovers like to entwine theirs arms when they are having talk.

2. Aqueducts (artificial channel to pass water)

There is lack of Aqueducts in Nepal for irrigation purpose.

3. Soaring (adjective)

The soaring of lending rates due to inflation which country like Nepal find hard to control.

4. Jeopardizing (V)

You jeopardizes the current condition.

5. Replenished 

He replenished the glass with the juice.

6. Dramatically

Dramatically surged in demand