To use or not use portable receptacles for baptism?

Why does God want us to be baptized?

Mark makes it very clear:

Mark 16:16 Whoever believes and is baptized will be saved,

The water by itself has no power, its just water! There is power in Gods word though (baptizing in the name of the Father, Son, and Holy Spirit). The water together with the word is how the Holy Spirit can work faith in your heart and you receive the forgiveness of sins.

Mark 1: 8 I baptize you with water, but he will baptize you with the Holy Spirit

So do you need water to receive faith from the Holy Spirit? No. Faith comes from hearing gods word.

Romans 10:17 Consequently, faith comes from hearing the message, and the message is heard through the word about Christ.

Why do we baptize with water? Because that is the tradition presented in the bible and Jesus command us to baptize.

Mathew 28:19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit

Since the water holds no power, the amount of it has nothing to do with what happens in baptism or why we baptize. The amounts are just man made traditions. Gods word commands us to baptize in his name. He says nothing about the amount of water.

Pertaining to evangelical perspective. I like the first entry for the definition of the word evangelical on dictionary.com. I am an evangelical Christian in the sense that I believe what the Bible says to be true. Evangelical has to do with believing the Gospel, that is the good news that Christ died for our sins. My answer references the gospel and good news. From a pure evangelical ( By pure I mean what does bible says about the matter, ignoring man made traditions) perspective you would look to see what the Bible says about a matter. In this case for baptism, power is in the Word and not the water. I realize evangelical denominations practice different traditions with water but from a pure evangelical point of view the water does not matter.

No, there is no such prohibition in any Christian group that I know of.

I have witnessed baptisms in various portable receptacles. It's normally done when there isn't a convenient alternative - for example in an Anglican church without a baptistry, and the candidate particularly wanted to be baptized by immersion.

I believe that baptisms can be held in any body of water, so a jacuzzi would do fine. What matters is that a person is surrounded by other believers and they are making the choice to be baptized for Christ.

It's about the heart and not formalities. Jesus never specifically talked about how we should do it. Just that it would be done. He didn't tell us not to use a jacuzzi, or to use a jacuzzi.

Therefore, go and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit. [Mat 28:19 NLT] Teach these new disciples to obey all the commands I have given you. And be sure of this: I am with you always, even to the end of the age." [Mat 28:20 NLT]

Answering your question begins with understanding what Baptism is; Baptism is an Earthly way of acknowledging a Spiritual rebirth.

From my Southern Baptist upbringing I offer my understanding of Baptism.

That having been said exactly what does baptism exemplify? The answer to that question is:

1. It is actually a burial ceremony, by that what I mean is that it exemplifies the death in payment for sin which God demanded in:

Genesis 2:17 but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die."

and it is our confession that Jesus death was in place of our second death.

2. it also signifies that we are now the recipient of:

John 10:27 and 28 My sheep hear My voice, and I know them, and they follow Me. 28 And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand.

And just as our emersion in the water is substitution for being buried in the ground; so the water is substitutionary of the grave.

It is the earthly acknowledgement of our Spiritual rebirth and the beginning of our eternal life in the Kingdom of God.

Most churches today have a built in Baptismal for two reasons:

1. The water temperature can be controlled which is a distinct advantage to being dunked in the river in the middle of winter.

2. The baptism is before the church and in the sanctuary of God.

As far as why not use other water basins I have seen baptisms take place in a cattle watering troth; and even in the Bible the baptism of the Eunuch took place in the body of water that just happened to be handy;

Acts 8:36 through 38 NKJV Now as they went down the road, they came to some water. And the eunuch said, "See, here is water. What hinders me from being baptized?" 37 Then Philip said, "If you believe with all your heart, you may." And he answered and said, "I believe that Jesus Christ is the Son of God." 38 So he commanded the chariot to stand still. And both Philip and the eunuch went down into the water, and he baptized him.

Notice that I have highlighted two very important requirements for baptism. That is what matters not the water that substitutes for the grave.

Hope this helps.