Posting Time is Here Again!

Doing it early for once, since I seem to have some modicum of inspiration.

The conquests of Alexander the Great had a major impact on the water-temples. At first, of course, their labors were disrupted. War always leaves long-term projects like theirs relegated to the background. But the most significant effects occured after the conquests were completed, and the Greeks began to take stock of just what, exactly, they had gained. Although Alexander was not, perhaps, the most competent civil administrator, his empire contained a goodly number of them. Greek bureaucrats and governers, eager to make their mark and gain the Emperor's favor, began to cast about themselves for ambitious projects to sponsor. From multiple directions, reports of the actions of the water-temples began to filter in. From Egypt, reports of significantly increased crop yields (up to 30%, in some luckier districts). From Babylon itself, demonstrations of improved irrigation, and the first tentative reports of success in desalinating fields. From the northern hills and mountains, proposals to divert streams and minor rivers to swell the amount of water available to the great waterways of Babylon.
Perhaps it was just a lucky coincidence; ten or more different administrators all suggesting things to use the water-temples for, all arriving on the same day. Or maybe Alexander noticed a pattern; his administrators kept mentioning these water-temples... Whatever it was, something caught Alexander's attention. Instead of handling the reports and projects piecemeal, he gathered the heads of ten of the most prominent water-temples together in Babylon, and proposed something to them: unification. Instead of each temple being an independent operator, allied to but separate from its neigbors, the temples would be a single, unified administration. They would have charge of all the water and irrigation in Alexander's empire.
The heads of the temples conferred (history claims for no more than 10 minutes), then returned an answer: an unequivocal "Yes!". Thus, under Alexander's reign, the temple of Zeus-Rain Bringer was formed (it was deemed politic to use a Greek god). The temples in the empire were now unified and part of the government.
Alexander died only 8 years later, but by then, the water temples had become a through part of the administration. They survived the power struggles surrounding Alexander's death, with each successor state simply inheriting the temples in thier territory. The temples in Greece fared less well than those in Egypt or Persia, being seen as a foreign Asian influence. In any case, the Greek terrain was less well suited to improvement by the water-temples' methods. However, the water-temples under the reigns of the Ptolomies in Egypt, and the Selucids in Persia, had great days. The centralized administration and vast resources allowed them to expand their projects, in many cases linking up. Particularly in Persia, the water-temples also began to work on very large scale engineering projects. Probably the most significant of these were vast resivores, designed like those in Egypt, but on a larger scale, that were built in Babylon and the surrounding cities. There, water was stored against dry years, and the irrigation systems was made even more organized and efficient. The temples introduced a number of major changes to the system to preserve water, including insuring that all main irrigation channels, and most minor ones, were covered to prevent excessive water loss through evaporation.
The water-temples in Persia proper also ran into another invention that they began to spread westward: the windmill. At first, it's transfer was slow. While the extra power could be useful in some situations, the water-priests had not yet found its "killer app", so to speak. Its time would come, but for now, it languished, half-forgotten in some cases.
In Egypt, meanwhile, however, another invention was causing a much bigger stir. In the mid-200's BC, word began to spread among the water-temples of a remarkable new invention: the Archimedes screw. This ingenious little setup could raise water from a low level to a higher one, much easier than hauling it up in buckets. Most of the North African temples found some use for it, but the greatest use was found by the temples in Egypt. There, their great water retention projects had always been hampered by the fact that the resivores could only be effectively filled once a year, when the Nile flooded. At other times, there was simply no cost-effective way of filling the resivores. Bucket hauling took far too much manpower away from other tasks, and rain was simply too infrequent.
The Archimedes screw changed all that. With it, a fairly large amount of water could be moved uphill, at a relatively low cost in manpower. When some bright temple apprentice observed that, by using waterwheels at the lower end of the screws in the Nile, the river itself could pump its water for them, the priests knew that they had just found answers for a hundred problems. No longer did the resivores run out months before the next flood season. Now, the growing season could be effectively extended throughout the year. As the resivores emptied, the screws placed in the Nile refilled them. Although the cisterns still emptied, there was always water within them now. Careful husbanding of it allowed constant irrigation. Egypt's productivity began to swell. Within a hundred years, it had achieved an almost 100% increase over the time before the screws.

Meanwhile, further west, the inventor of the new devices, Archimedes himself, was about to have a fateful encounter with the water-priests.
The empire of Carthage had been fairly good for the water-priests. The merchant-princes of the city had been well aware that the water-temples kept their local hinterland productive and green. The temples had recieved generous donations, and were often encouraged to establish new temples in Carthaginian client cites and colonies. Thus, water-temples had spread to Sicily, where they had first encountered the Archimedes screw, in Syracuse. They had spread it from there, and the water-temple in Syracuse was well aware of the value of the inventor of the device.
When the Punic Wars began, the water-temples kept a careful policy of neutrality. They liked Carthage well enough, true, but Rome was obviously on the rise, and they, paricularly the temples in Sicily, had to be cautious not to be caught in the middle. The water-temples took refuge in their historical independence. Whenever a Roman general, or a Carthaginian one, took issue with reports of water-priests helping the other side, the temples he took his complaints to could always point out that they were unable to compell obdience from other temples, and that they had never yet been proved to be transfering vital information to the enemy.
This allowed the water-priests, during the Second Punic War, to be relatively trusted by the Romans. They had found that, in their governership of Sicily, that the water-temples had been very cooperative. In fact, the water-priests had often been overjoyed at the engineering skill exhibited by the Romans. Their irrigation projects went smoother, were sturdier, and were more extensive, when the Romans were behind them.
As a result of all this, the Roman general Marcellus was receptive when a delegation of water-priests came to him with an offer. They wanted Archimedes preserved at all costs, if Syracuse was conquered. Marcellus had his own desires in this direction, and with the signifcant bribe offered by the water-priests, he not only ordered Archimedes taken alive, he threatened dire punishments to anyone who killed him, including execution, the selling of his family into slavery, and the decimation of his unit.
These threats proved effective, and when Syracuse was finally conquered, Archimedes was not killed, as he was in our timeline. Instead, he was brought to Marcellus (after finishing the equation he had been working on when the soldiers burst in), and the general proceded to have a talk with the philosopher. He came away looking rather confused, it is generally reported, Archimedes being of the opinion that pretty much everything the general wanted to know about (claws that could lift ships, levers for moving the world, etc.) were essentially toys, distractions from the true work of mathematics. Luckily, the water priests were somewhat more patient. They were willing to sit though endless hours of mathematical lecturing, if it meant more things like the Archimedes screw. In fact, some of the younger priests even found the math fairly stimulating. However, the most immediate effect did not even come from something Archimedes directly told the water priests. History has recorded the tale thusly.
One day, five years after the end of the seige of Syracuse, a young priest was lounging about Archimedes' home, after a rigourous morning of math (he had been learning integral calculus, although he didn't call it that). Glancing about, he noticed a bronze mirror laying on a table. Being a rather vain man, he picked it up, ready to check his face for blemishes. To his dismay, he found the mirror was concave, distorting his face most horribly! Dissapointed, he turned to Archimedes and asked why the old philosopher had such a useless thing lying about? Archimedes replied that it had been an old trick he had worked out. He explained that if the mirror was created correctly (here he rattled off some formulas describing the proper curve the mirror had to be set to), it could seemingly concentrate the heat of the sun. He mentioned, rather casually, that it could even light something on fire, if held long enough. He had apparently contemplated using larger versions during the seige, but could never get the creation process to scale up properly; the craftsmen simply weren't good enough to create big enough mirrors. Oh, well. It had been a thought, and besides, it had turned out to be futile, anyway.
The young priest, meanwhile, had mostly stopped listening after the part about "heating things to the point of burning". His mind was racing, and as soon as he could politely excuse himself, he was racing himself, to get back to the temple. There, he quickly sent an apprentice for a bowl of seawater. While that was being found, he did some tests, and quickly found the focal point of the mirror (earning himself a scorched finger in the process). When the apprentice returned, he was set to holding the light over the bowl of water, carefully keeping the focal point on the surface. Within the hour, the priest was sure: the level of the bowl was distinctly lower, a salty residue had formed, and the apprentice's arm was dead tired. Not that the priest cared. He rushed to tell his superiors the good news.
For some time, the priests had understood the concept of evaporation, if not the exact mechanics of it. Water, exposed to heat, vanished, leaving behind anything in it that wasn't water. Evaporation had nessecitated innovations such as covered irrigation channels, and the universal practice of providing any open body of water with as much shade as possible. But evaporation was recognized as not a univeral drawback. The principle of purifying water by evaporation was also widely understood. In fact, some temples, closer to the coast, had tried to increase their water supplies by boiling salt water, and collecting the steam. They had been stymied by the cost of wood for heating. And evaporation from sunlight was simply too slow. But here - here was a way to concentrate the sun, to force it to heat water faster! In addition, the salt left by evaporating sea water was valuable. This new method promised not only to increase the amount of water avaiable to the temple, but to increase its profits above and beyond that provided by water, as well.
A test area was quickly set up. Although local Syracusian craftsmen had not been able to create significantly larger mirrors, the water-priests had wider resources. The money of the temples brought in some of the finest bronze casters in the Mediterranean, and Archimedes casual provision of the formula for finding the focal point proved invaluable. Soon, mirrors up to 3 feet across were being created, and set up. Some research into the mirrors determined that a convex mirror, properly set up, could be set up in the focal point of a larger mirror to create a beam that was capable of being bounced off normal mirrors, still retaining its heat. Soon, a small operation was underway on the coast. Resivores were hollowed, with connections to the sea. Each resivore was set up so that a strong heat beam was reflected in through a hole low in the side. Meanwhile, passages higher up, on the roof, led to a second, dry cistern. As the light was shone in the hole, the priests waited expectantly. By the end of the first day, a foot of water was already collecting the second resivore. Cautiously, the head priest took a glass from it, and tasted it. His smile told his fellow priests all they needed to know. The water was fresh, and they had a new method of getting clean water...