CRAFTING POWER
At this point you're probably thinking to yourself, "Holy crap, I'm gonna need a ton of power to craft all these mother loving recipes on Free Water Day!"
You are correct to think this, so score yourself two bonus points.
Power maximization, optimization, utilization and management are all big words with which you should familiarize yourself. Here are some power tips to help make your Free Water Day crafting dreams a reality:
GET A WINDMILL
If you are level 35 or above, you can opt to purchase a level 1 Windmill from the Big Harvest upgrade menu.
I recommend that you do so, and then upgrade it as far as you are able. You receive +10 bonus power per harvest from the initial level 1 Windmill, and then +5 additional bonus power per harvest for each successive level upgrade thereafter.
RESERVE POWER
Another good idea is to avail yourself of any opportunities to store extra power in your inventory that you can use on Free Water Day.
You can store up to 30 individual powers, plus up to 100 each Power 5 Packs and Power 10 Packs. You can earn Power Packs from certain quests, watching certain pop-up advertisements while playing the game and also from taking certain surveys offered by Zynga (Find these at Zynga's FarmVille 2 Facebook page, blog and Twitter). Check your inventory, you may already have several on hand of which you were not aware! What a lovely surprise.
FARMHANDS AS POWER TOOLS
Another untapped power source that may not have crossed your mind is farmhands. If it did cross your mind, then please forgive my hypothetical presumptuousness. Otherwise, read on...
You know those cute little people sitting on your hay bales out front that you usually use to water or speed grow your crops? Well those are your farmhands, and on Free Water Day you're not going to need their help watering any crops; and if you're just going to be growing one or two minute crops, you certainly won't need them to speed grow anything. So what can you do with them? Well you can ruthlessly murder them in exchange for free power, that's what!
To do so, all you need to do is pick them up one by one and sacrifice them to the Cornfish God by dropping them directly into your oven through the chimney of your Crafting Kitchen.
This will burn each farmhand alive, earning you sacrificial remuneration in the form of 5 power for each of their otherwise worthless souls.
Isn't this painful for the farmhand? Hell yes it is, but they are happy to do it. Go figure! Zealots.
Anyway, if you have eight hay bales, that's 40 extra crafting power you can squeeze out of your farmhands each eight hours. If you can time it so they show up at your farm three separate times during Free Water Day, that gives you access to an extra 120 crafting power, which is nothing to sneeze at.
CRAFT WISELY, MY FRIEND
One final word on power management strategy: Although you may be tempted to craft lots of lemon water, lime water, pottery slips and other things that consume a single drop of water, consider avoiding those recipes and focusing instead on those which require multiple drops of water, such as broth, dough and rose water. While your water supply will be unlimited, your power supply will not, so these recipes will give you the most bang for your crafting power buck on Free Water Day.
ANIMALS & FERTILIZER
You will have to decide for yourself if you will fertilize your crops on Free Water Day. I will be doing so and I would suggest that you do as well. But again, it's entirely up to you.
DOUBLE DOWN
Some people say "Oh I don't care about the County Fair, so I don't need to fertilize my crops." That's fine, but these people may be overlooking the fact that fertilizer not only gives you a chance at a prized crop for the County Fair, but it also doubles your crop yield. So, for every fertilized crop you harvest, you will receive two goods instead of just the one you would have received without fertilizer.
Yes, you read that correctly. For every tomato you plant, water and fertilize, you will harvest two tomatoes! Since two is better than one, it makes sense to fertilize your crops to get the most bang for your buck.
Remember, you have unlimited water on Free Water Day, but you do not have unlimited time. You want to stock up on as many crops as you can grow and harvest in the time allotted before you either pass out from exhaustion or Free Water Day ends, whichever comes first. Therefore, fertilizer is your best bet to maximize your crop yield during the limited time that free water is available to you.
MASTER FASTER
Another thing to consider is that harvesting fertilized crops grants you more Mastery Points than harvesting unfertilized ones. So if you're looking to finally earn that very elusive and long sought after blue ribbon in crops such as radishes, then fertilizing your radish crops will help you get there quicker.
Now that we've settled the question of how useful fertilizer can be on Free Water Day, we come to the sobering realization that we are going to need a LOT of fertilizer. We're talking tons and tons of it!
So we need to decide now which animal will give us the most fertilizer. Some people will tell you to get buffalo, while others express a great fondness for their Gold-Laced Cochins, and those who are lucky enough to own limited edition New Hampshire chickens swear by those.
But I don't have any of those fancy NH chickens, the buffalo doesn't drop enough fertilizer to make me happy, and Cochin fertilizer drops are not very consistent; so for my money the Black Arabian Horse is the best bet.

These babies guarantee you four fertilizer per feeding and help fill up your fertilizer bin pretty darn swiftly as well. You can't feed them as often as a buffalo or chicken, but if you stock up on Super Feed and also ask your neighbors to feed them when they visit, this shouldn't be an issue.
SUPER FEED IS SUPER
Speaking of Super Feed, you can only make up to five of them each eight hours, so you had better get started on that right away!
You may have already noticed that Super Feed is not quite the same as the old Speed Feed was, despite the fact that they mistakenly use the terms interchangeably in the guide I've linked to above.
Feeding an animal the new Super Feed is different and awesome because it triples the animal's resource output! Therefore, Super Feeding your Black Arabians will give you twelve fertilizers instead of the usual four!
So, needless to say, my advice is tell all your animals who are not Black Arabian Horses to take a hike. They won't be happy about it, but screw 'em. It's your farm.
When they're all gone, replace those useless old animals with your beautiful brand new Black Arabian Horses!
GET THE MESSAGE?
It is imperative that you alert your neighbors to the fact that you want your horses fed when they visit you on Free Water Day.
There are several methods you can employ to accomplish this, such as posting a nice Facebook message politely specifying what you wish your neighbors to do, renaming your farm to something like "FEED HORSES," or using the sign you earned during the Bake Sale quest for same, should you happen to have one.
Just keep in mind that most of your visitors will completely ignore these messages and signs and just harvest your tomatoes instead.
Try to refrain from yanking clumps of your own hair out in frustration and just roll with it. You'll have plenty of time to plot your revenge later.
RAKING IT IN
Feeding all those hungry horses repeatedly on Free Water Day will inevitably result in many trips to the fertilizer bin. Therefore you're going to want to craft a full supply of fertilizer rakes long before the event begins so you can save your crafting power for water-based recipes.
If you have a bit of heirloom wood stocked up, you can use the double rake recipe in your workshop to get two rakes for the price of one.
GIVING AND RECEIVING
Although I have advocated using your mailbox to send a free gift of water to your neighbors each day, Free Water Day is the one day when this won't be necessary. On this day, please be sure to send your neighbors a free gift of fertilizer instead. Sending your neighbors water on Free Water Day would just be dumb. You don't want to look dumb, do you? 'Course not. Send fertilizer.
If you have good neighbors, they will surely reciprocate and send you back some fertilizer too! On the other hand, if you have not-so-good neighbors, they will send you a wood plank. Unfriend such neighbors immediately -- You don't need that kind of negativity in your life.
Of course, if you happen to run out of fertilizer during Free Water Day, you can always ask your friends for some more after adding any reserves you have stored in inventory to your active supply.
Since you can do this once every 18 hours, and since Free Water Day lasts for 24 hours, if you time it right, you can score yourself a sweet double helping of fertilizer. Math it.
PLOTS, FIELDS, CROPS & TREES
You're going to want to maximize the space on your farm to accommodate as many plots and trees as possible.
So expunge all superfluous decorations from your farm, except for your Cornfish God shrine, for it is sacred and will spiritually ensure bountiful harvests.

You probably spent a lot of time and effort decorating your farm, so storing all those lovely decorations in your inventory is bound to sting a little bit. But this is Free Water Day, and you need room to grow. So bite the bullet.
On June 10th you can get rid of all these extra plots and redecorate your farm if you want. It was long overdue for a fresh new look anyway, wasn't it?
FIELD OF DREAMS
The new Big Harvest fields should prove especially beneficial on Free Water Day for several reasons, so I would recommend that you buy as many of these as you can afford and upgrade them as far as you are able.
Here are some of the ways fields can benefit you on Free Water Day:
1. Space-saving. With a field you can fit five plots in the same space as four. So this will help you get more crops and trees on the ground during Free Water Day.
2. Time-saving. With fields you can plant, water, fertilize and harvest 5 plots at once. So it's 5 times faster than a standard plot in every imaginable way. Celerity will be absolutely key to getting the most out of Free Water Day, so this is a biggie.
3. Bonus-producing. Each successive field level yields a +1 bonus crop. So planting and fertilizing 5 tomato crops in a level 1 field will give you 11 tomatoes upon harvest. A level 5 field would yield 15 tomatoes. That's 5 extra tomatoes! Imagine how many BLT's you could make with that.
4. There might be a fourth benefit to fields, but it currently eludes me. Oh yeah, your bees will fertilize 5 crops instead of just 4 by using them on a field. So that's pretty cool I guess. Also, according to something I just noticed in the graphic below, fields apparently help you master faster. Now that I know that I'll be growing all my pesky radishes in fields. See, I'm learning new stuff too!

I only have 9 fields at the moment because I squandered all my favors on other silly things. I regret that now. Don't be like me. Buy and upgrade many fields.
MONEY CROPS
The stars of the show on Free Water Day are going to be your six 1 and 2 minute crops: Tomato, Blueberry, Corn, Radish, Blackberry, Turnip. Look at them. Aren't they gorgeous?
Grow them all and stock up on as much of each as you can, but you may wish to give some extra attention to certain ones. Namely, those of which you have not fully mastered, and/or those which will help you complete some pending Big Harvest orders and/or those which are the most popular recipe ingredients (all but Radish and Blackberry). Coincidentally, it appears that those two least popular crops are the ones I'm going to need to grow the most of to master. Oh well.
Once your mouse-hand starts getting numb, or you grow sleepy or hungry, you're going to need to take a break. Depending on how long you plan to be away from your computer, consider planting some short-term crops in the one to four hour range before you go.
1HR: In the 1 hour category you have Rye or Chickpea to choose from.
2HR: Two hour crops include Chardonnay Grapes, Ginger, Squash, Barley, Mint and Cassava.
4HR: And four hour crops are Wheat, Eggplant, Spinach, Quinoa and Azuki Bean.
WATER CROPS
You're kidding, right? It's FREE WATER DAY! Forget about water crops!
In fact, you should probably just delete all your river plots until after Free Water Day is over so none of your visitors get any bright ideas.
TREES
As soon as the free water starts flowing, water all your groves and trees. Pull as many elders out of your inventory that will fit on your farm and water those too.
I could go on and on about which trees are best to water (rubber and wood) and stuff like that, but I'm tired of typing this thing and I just want to go prepare my own farm now. So suffice it to say:
W A T E R E V E R Y T H I N G ! ! !
It's Free Water day, after all. Whip out all them trees and get 'em wet!
SPRINKLERS
I dunno, it's up to you I guess. Probably save you some time watering crops. Do what you want. I don't think anyone has read this far down anyway.
FERTILIZER PLANE
This thing will probably save you some time too, fertilizing nine crops at once. Plus it gives you a chance to win some bonus fertilizer, so go for it. It's not like you're going to be needing the fuel for your crop dryer on Free Water Day, right?
LAST MINUTE PREPARATIONS
You only have a few more things to do in the final hours leading up to Free Water Day in order to be fully prepared. These last minute preparations will be more about preparing your life than your farm.
CALL IN SICK
First thing you're going to want to do is call in sick for work. Are you seriously going to want to spend 8+ hours at work while all your friends are at home enjoying their unlimited free water? Heck no.
If you're the guilty-feeling type who doesn't like to lie to your boss, just tell them you have been diagnosed with Hydrocephalus (also known as "water on the brain.") It's true, right? Because Free Water Day is all you will be able to think about for the next 24 hours!
GET RID OF YOUR FAMILY
Family is nice to have around sometimes so you don't get too lonely, but on free water day they are just going to bug the hell out of you with all their "wants" and "needs" and "love" and "attention." Gah! Who needs that crap? Get rid of them!
Send your spouse on a little vacation; perhaps a nice relaxing cruise.
Next, drop the kids off at a neighbor's house. They say it takes a village to raise a child, so any nearby doorstep will do.
REST UP FOR THE BIG DAY
Next thing you want to do is take a little cat nap or two. You're going to be up all night farming like you've never farmed before, so you need to get all the rest you can get beforehand.
Doesn't matter where you do it, just grab a few precious Z's and you'll be good as new. But just don't forget to set your alarm cock first. You wouldn't want to oversleep and miss Free Water Day!
IT'S ALMOST GAME TIME!
Once you awaken from your nap, it's time to get serious. Free Water Day is going to begin any moment now. So brew a big strong cup of coffee...
...and maybe even take some NO DOZ to help you stay awake.
Lastly, post a message on Facebook to warn your friends of what will happen if they try and water any of your crops on Free Water Day:
Oh that reminds me, if you're the poetic type, I made some nice little graphics you can download and post on your Facebook. Just right click these and then select "Save image as..." to grab a copy for yourself.
CONCLUSION
Well, I think that pretty much covers everything, except for all the stuff I probably forgot to cover. So if I missed anything, or if you have your own cool Free Water Day tips, feel free to post them in the comments section below.
I hope that you enjoyed these little tips, and I wish you all a wonderful Free Water Day!
Please note: No animals were harmed in the making of this blog post.
(But several farmhands were mercilessly incinerated.)
UPDATE: I posted a small update to this post on June 9 at ~4pm PST with a few random FWD thoughts. You can find it here: Head Above Water.